I have a rb2011 is it normal to turn off when moving the power cable?
no, it’s not normal.
if it is the 1st rev (the DC connector is inside the body) - it may be because the DC plug is not sitting firmly in the socket. it was a common problem. the plug is inside, and if you grab on the cable it may slips out, but this is not noticeable from the outside. you may try to push it back in (it’s tricky), or take the box apart (if desktop version, watch out for the LCD cables), and re-seat the plug into the connector. and you may install a wire stress-relief on the cable to prevent similar issues.
if it’s the 2nd rev, which has a proper DC connector on the back of the housing, then you may have a broken cable, that sometimes does not conduct. when moved, previously attached wires come apart. you may need to put a new 5,5/2,1 DC barrel jack on the end of the cable.