Makita hm 1800 green light on hand switch engauged nothing happens

I would say it has stripped a gear and it jammed up. If this has happened , it would be cheaper buying a new drill. Try using a pair of multigrips to force the chuck around. If you get it free and the drill runs again, it could have just "jumped a tooth" and may be OK. If it crunches and locks up again, its rubbish bin time.

The motor is bad from overheating. Have motor rebuilt or replaced.

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better have the transfer case inspected, could be low on grease or in need of maintenance

hi
it sound that the generator has blown the rectify on the charger unit

Look for sloppy contacts on the battery

MAKITA HAMMER DRILL GREASE 30G (181490-7) or for the older HM models Hammer grease Makita P-08361

As stated in the manual:
The green power-ON indicator lamp lights up when the tool is plugged to the mains. If the indicator lamp is lit but the tool does not start even if the tool is switched ON, the carbon brushes may be worn out, or the motor or the switch may be defective. If the indicator lamp does not light up, the mains cord or the indicator lamp may be defective.

From the owner's manual: Indicator lamp The green power-ON indicator lamp lights up when the tool is switched ON. If the indicator lamp is lit but the tool does not start, the carbon brushes may be worn out, or the electric circuit or the motor may be defective. If the indicator lamp does not light up and the tool does not start, the ON/OFF switch or the mains cord may be defective.

The easiest to check is the brushes. Most newer tools have brushes with a spring loaded pin in them so when they wear down the pin pops and stops the motor so you don't wear the armature. Even without the pin the wire from the contact to the brush is short so the spring doesn't contact and ruin the armature. If the brushes are OK, you'll have to check the switch for continuity.

What kind of oil is used in a Makita Demolition Hammer?

should have some kind of fault light on to read fault codes

its mostly an electronic solenoid shift system
could be a transfer box fault