Welcome to iRV2. Most of the RV slides work from 12 volt DC ( VDC) power. Most new batteries are charge enough to work the slide when you buy them. Do you have a volt meter and know how to read the battery voltage? It should be over 12 volts and maybe as high as 13.8 while hooked to the 120 volt AC (VAC) power.
If you have power at the battery, you need to start tracking down how far you have 12 volt power. Check the fuses as the slides are on a separate 12 volt fuse. Can you hear a motor running? If the motor is running, you have a broken shear pin or a stripped gear.
Let us know what you find.
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