[screwdriver]

the g&g gr25 is semi auto only, no full auto option even though other copies of the sr25 sniper rifle are.
you say you can hear the motor turning, if its only the motor there will be a high pitch/speed whirring noise. if this is the case remove motor and see if drive gear has stripped/fallen off.
if okay check motor depth adjustment (grub screw in motor cage).
you say you cant pull trigger, this on mine was caused by semi auto latch in gearbox sticking which is why i removed it creating full auto only.
you could try removing motor and with a hooked piece of wire release anti reversal latch then replace motor and then try to fire gun.
a problem ive found with alot of guns in semiauto is that if you dont pull the trigger back fully every time and wait till gun has fired before releasing ,the gun can stop half cycle meaning the semi latch will jam the trigger.
this is where on a gun with full auto option will clear the jam as the lever is disengaged