I don't own one of these. But on most remote-controlled units, the power switch can't power off everything; otherwise you couldn't turn it back on with the remote. A minimum amount of circuitry remains powered even after you hit the power switch. That would explain the brief display flashes, and may be why unplugging it has a different effect than using the power switch.
Of course, if you find yourself power-cycling the unit frequently, there's nothing to prevent you from splicing a lamp-cord switch into the power cable, using a power strip with a switch, etc. You could even plug it into one of those timers and set it to power off for a few minutes every night (just choose a time when you won't be recording anything).