Found this information on the RCA 10 Viking Pro Repair page at ifixit.com in the User Manual.pdf on Page 30:

-Tablet is frozen or a serious error appears-

If the tablet is frozen or suspended, you may need to close the app program or reset the tablet.

If the tablet is frozen or slow to respond, press and hold the power button for 8 seconds to reset the tablet. (This is what fixed the problem on my RCA Voyager Pro, and I had to sit through about a minute or two of waiting for it to start up, again, but the Slide Up unlock feature finally started to work after doing so)

If that doesn't work, press the RESET button at the back of the tablet; then press and hold the Power button for 4-5 seconds to turn on the unit.