My hyndai elantra 2010 locked became unlocked when person remotely unlocked their car next to mine

2010 camaros only have one central switch just under the radio. It operates a relay that controls the actuators in both doors. Run a trace to eliminate a faulty relay, blown fuse or bad switch. If the doors lock and unlock using the remote I doubt it's the relay. Check the door settings does it unlock when car is shifted into park? If not check settings. Refer to your manual for details of how to set locks.

The Headlamps On at Exit and Perimeter Lighting modes can be adjusted using the steering wheel controls to select the wanted function as displayed in the driver information center. The Headlamps On at Exit selection will allow the driver to customize the period of time that the headlamps remain illuminated upon exiting the vehicle. This period can be adjusted from 0 seconds to 180 seconds. The Perimeter Lighting feature allows the driver to select if they want the headlamps and backup lamps to illuminate when the door UNLOCK button on the key fob is activated. This feature can be turned ON or OFF by using the driver information center steering wheel control buttons.
programming Features with the Driver Information Center (DIC)
To enter programming with the driver information center (DIC), perform the following actions:
Turn the ignition to RUN.
Place the vehicle in PARK.
Press the Personalization button on the steering wheel to enter personalization programming.
Automatic Door Locks
Continue with the following steps in order to personalize the automatic door locks:
Press the Select button in order to enter the menu. The first choice seen is the current setting.
Press the Select button in order to scroll through the following options:
• LOCK DOORS: IN GEAR
• LOCK DOORS: WITH SPEED
Press the Personalization button in order to advance to the next option.
Press the Select button in order to enter the menu. The first choice seen is the current setting.
Press the Select button in order to scroll through the following options:
• UNLOCK DRIVER: IN PARK
• UNLOCK DOORS: IN PARK
• UNLOCK DOORS: AT KEY OUT
• UNLOCK DOORS: MANUALLY
Press the Personalization button in order to advance to the next option.
Remote Activation Verification
Continue with the following steps in order to personalize the remote activation verification feature:
Press the Select button in order to enter the menu. The first choice seen is the current setting.
Press the Select button in order to scroll through the following options:
• LOCK FEEDBACK: BOTH
• LOCK FEEDBACK: OFF
• LOCK FEEDBACK: HORN
• LOCK FEEDBACK: LAMPS
Press the Personalization button in order to advance to the next option.
Press the Select button in order to enter the menu. The first choice seen is the current setting.
Press the Select button in order to scroll through the following options:
• UNLOCK FEEDBACK: BOTH
• UNLOCK FEEDBACK: OFF
• UNLOCK FEEDBACK: HORN
• UNLOCK FEEDBACK: LAMPS
Press the Personalization button in order to advance to the next option.
Delayed Lighting
Continue with the following steps in order to personalize the delayed lighting feature:
Press the Select button in order to enter the menu. The first choice seen is the current setting.
Press the Select button in order to scroll through the following options:
• HEADLAMP DELAY: 10 SEC
• HEADLAMP DELAY: 20 SEC
• HEADLAMP DELAY: 40 SEC
• HEADLAMP DELAY: 1 MIN
• HEADLAMP DELAY: 2 MIN
• HEADLAMP DELAY: 3 MIN
• HEADLAMP DELAY: OFF
Press the Personalization button in order to advance to the next option.
Perimeter Lighting
Continue with the following steps in order to personalize the perimeter lighting:
Press the Select button in order to enter the menu. The first choice seen is the current setting.
Press the Select button in order to scroll through the following options:
• PERIMETER LIGHTS: OFF
• PERIMETER LIGHTS: ON
Press the Personalization button in order to advance to the next option.

If Your 2007-2010 Silverado Has a VIC - Vehicle Information Center Step 1: Sit in the vehicle with all the doors closed and unlocked. Start your Silverado and leave it in Park.
Step 2: Press and hold the Vehicle Information button, marked by an image of a car and the letter "i", until the display reads "Press V to Relearn Remote Key".
Step 3: Press the Set/Reset button until "Remote Key Learning Active" appears.
Step 4: Simultaneously press and hold the Lock and Unlock buttons for 15 seconds. A chime will sound indicating the remote has been successfully programmed.
Step 5: Program additional remotes by repeating Step 4 for each fob.
Step 6: Exit programming mode by turning off the vehicle and removing the key.
Step 7: Test your remote(s).
If Your 2007-2010 Silverado Doesn't Have a VIC - Vehicle Information System Step 1: Sit in the vehicle with all the doors closed and unlocked. Turn the key to Accessory Power position.
Step 2: Press the trip odometer meter reset stem repeatedly until you see "Relearn Remote Key".
Step 3: Press and hold the trip odometer meter stem for three seconds. The display will read "Key Learning Active".
Step 4: Simultaneously press and hold the Lock and Unlock buttons for 15 seconds. A chime will sound indicating the remote has been successfully programmed.
Step 5: Program additional remotes by repeating Step 4 for each fob.
Step 6: Exit programming mode by turning off the vehicle and removing the key.
Step 7: Test your remote(s).

do they work when using the master switch on the drivers door panel? if only the drivers door unlocks when pressing the button, it may be a personal setting change needed. in this case usually pushing the unlock button on the remote twice will then unlock all doors. if there is only one lock that doesn't work it is most likely the door lock actuator that is at fault or a broken wire in the door opening wiring harness of the door that the lock does not work on.

Possible issue with the remote controller unit - main board or sub assemblies. The intermittent behavior seems to indicate that the board is erratic to detect at the same time the individual locks work at times.
So make sure all the connectors to the door and to the main board controller are tight. You can remove the main unit and check for any loose connections or clogging, specially water in all the door units or in main unit. If so dry and test.
Otherwise the main unit is a suspect.

You need new battery/s for your remote.

you have to press it twice to unlock all doors or lock all doors.

most likely a bad power lock switch, just replace it with a new one.

Drain some out !! And re-fill it..

Over fill will blow out seals & gaskits and causemajor leaks..

When you are filling it.. The car should be running in park.. The dipstick messures in pints - not quarts..

Rate well ;o)

The calipers on the disc brake models do seize commonly either staying on,as in locking the wheel or not braking that wheel at all.