There is a built in "Anti-Trap feature" designed to inhibit the screen
from moving if any obstruction is detected.
Try removing the Screen and seeing whether it does the same when you turn the Ignition on ?
There is a possibility that the screen has been mounted in such a way,
due to the mounting holes being slightly enlarged, as to put some strain on the operating arms,
and coupled with the lower voltage when the engine is not running,
could be preventing the correct operation.
If the screen arms move correctly without the screen fitted, replace it and pay attention
to lining up the holes with the bolts as much as possible to the screen arms
are not moved away from their resting position.
I would also have your Battery professionally tested to make sure it is good,
and is providing the correct voltage and current output without the engine running.
Cheers

