Thank you everyone for your very useful comments 👍 Especially the warning about the motor!

The property is in need of repair and was abandoned for a while; I am slowly trying to improve what I can without spending any money (if possible).

The garage door was previously operated by a remote control; when it worked it was intermittent and there is no other exit; I was often worried someone could get trapped in there; especially if there was a power cut. I enquired about a crank, as there is a socket, but this would only work from the inside and the crank would be very slow to operate.

Unfortunately the motor no longer works, I replaced the battery in the remote and tested to be sure. I don’t have the money to replace anything, and if I did, I would probably prefer to just buy a manual ‘tilting’ garage door type.

At the moment the door is up/open, and has been for several years (the photo is old), I am currently using the garage to store wood for now.

I don’t think the door is too heavy; I think it would be possible to lift it/modify it. The photos are not so clear but the metal is thin, probably aluminium. Although it would certainly require some effort to lift and would most likely slam down without some support.

If it was safe to remove the motor and easy to lift/support I may have considered some modifications using what I have lying around. But I am thinking given the danger/cost/effort it may stay as it is for now until I have some money to replace it completely with a tilt door.

Thank you all again for your advice, this is a great first experience here.