Velux windows stuck in open vent position

I have 3 velux windows in my kitchen cieling and they have been stuck in vent position for ages.

They are the solar remote controlled ones. About 8 years old. The remote no longer works on one of them and the others make a noise then stop.

Ive tried to close the vent manually one one and have snapped one end where the hinge is screwed to it. I did really force it to be fair. On another i've tried to fully open it and can't (almost hung off of it pulling) I presume the latches are siezed.

Ive watched a video on how to release the chain from the solar motor but I can't actually see or get to it because the window won't open.

Has anyone any suggestions on how to release them so I can clean/oil everything

Ive managed to feel my hand round the back and release the chain. The window then opens. the two latches dont feel seized but the middle lever that pushed the latches (bit attached to the vent bar won't move).

Ive pushed the latches down and out which then allows the bar to move up and close the latches. I presume this is how it locks.

The solar chain attachment is still stuck out so window won't close. Ive located a reset button which upon pressing with a paper clip pulls the chain back in. The window will then close.

Ill follow the reset procedure with the remote and see if they function properly again.