You need to release the torque nuts and with help manually push in the slide.
A crows wrench is used to release them and they have two torque values 125 & 145 lbs.
In
QT's 1 & 2 all slide information is located and this is the
old slide spec.
With the slide in your compartments will have motor and shaft exposed to work on.
You may need to check the motor location wiring to see if you have the 12 volts for motor operation and did not break the gear housing or blow the fuse.
If you can get the motor working you can try to move slide in or out and see if the slide reorients itself, if you accidentally forgot to release the locking bar that may not work and the nuts will need to be released.
You can drive the MH to a dealer to have fixed as long as its not raining.
All the links below in my signature have information for your Newmar.