Tom Tom 300 Green power light comes on but no screen display

if all you are getting is a green light and no screen coming on, you have blown one of two chips inside it by using a dodgy car charger

First you need to check if the battery is okay, try it on another tom tom gps receiver, if it is working and the screen wont turn on, then it means there is a hardware problem, probably the flexi ribbon that is connected to the screen is either loose or bad, this will require you to disassemble the tom tom and check for the flexi ribbon that connects to the screen, then you resit it or change the ribbon, that should do the job.
You can also try to reset the tom tom first before disassembling it. By pressing and holding the power on/off button for about 15 seconds, if that does not do the job, then you can go ahead and disassemble the tom tom.
Hope this solution helped

Try doing a device update while connected to tomtom home, if that doesnt work backup your device onto your commputer and try reinstalling the software and maps ect onto your device.

try a battery replacement

solution was posted here

hello, this problem and answers is covered under the TomTom Go 300 section. Please take a look there to get an answer. Its very comprehensive.

Remove battery and disconnect from power for 5 minutes, also remove map card, this will reset the device. Try it out
click;

Repair4GPS: How to Clean, Upgrade, Repair, Mod, Disassemble a GPS ...

see here

http://www.tomtom.com/lib/doc/legal/lw/LW-English-US%20CAN.pdf

To only way you can fix it is taking apart the Tom Tom, checking if the flat ribbon cable and connector to the screen are well in place and eventually replace the display ($80 on Ebay).
Unfortunately this will invalidate the guaranty, and you risk to damage your GPS if you are not a really experienced DIYer. Tom Tom offer one year full guaranty on all their receivers.
Contact Tom Tom and get it repaired:
Support URL: http://www.tomtom.com
Support Phone Number: 978.287.9555
Support Email Address: [email protected]


Hope this may help;

DON'T FORGET TO RATE:

Go to:
http://www.tomtom.com/support/index.php?Language=1&query=reset&FID=6965

Follow instructions...

If the unit is still under warranty, send it back to Tomtom. Even if the unit is no longer under warranty, complain to Tomtom. There is a problem with the CLA (cigarette lighter adapter). It can cause internal damages to your Tomtom. What happens is that there are three wires in the CLA along with a voltage stepdown circuit board. The wire are +, -, and a signal wire. If the signal wire get disconnect the voltage could spike up to 12vdc. The unit is designed for only 5vdc.

If the unit is out of warranty then try the following website for repairs. They can fix the two chips which usually blows.

http://www.satnav-shop.com/

Hi,
Press the power button for 15 seconds and your tomtom will turn on with the drum sounds yor tomtom will now reset but nothing will be deleted off it and it will now hope fully work.

Bye