im no expert but it sounds like your trans is gonna have to come back out
and if it really is stuck in reverse you might grenade it shifting into a gear
it honestly sounds like reverse is engaged always and the reason you cant move the sifter to the right is because thats 5th and reverse. and the shift fork is engaged so now its blocking the shifter itself from going that direction.
The red squares are supposed to be the shifter as if it were engaging reverse to show you how it would block you from moving the shifter to the right