you said, you deleted the key ==> a hardreset should solve that, but you also said that you couldn't perform a hardreset, so plugging out battery should solve that. Probably, but I really don't think so, this device has some backup Battery installed, you should plug out battery at least for three days. If you don't want to wait that long, rewrite your script and copy down registry folder loader to SD Card. My assumption is that the key is there should look like this one
HKEY_LOCAL_MACHINE\Loader]
"SystemPath"=hex(7):\
5c,00,53,00,74,00,6f,00,72,00,61,00,67,00,65,00,20,00,43,00,61,00,72,00,64,\
00,5c,00,4d,00,69,00,6f,00,41,00,75,00,74,00,6f,00,52,00,75,00,6e,00,5c,00,\
53,00,79,00,73,00,74,00,65,00,6d,00,5c,00,00,00,5c,00,53,00,74,00,6f,00,72,\
00,61,00,67,00,65,00,20,00,43,00,61,00,72,00,64,00,5c,00,4d,00,69,00,6f,00,\
41,00,75,00,74,00,6f,00,52,00,75,00,6e,00,5c,00,53,00,79,00,73,00,74,00,65,\
00,6d,00,5c,00,43,00,45,00,35,00,5c,00,00,00,5c,00,53,00,74,00,6f,00,72,00,\
61,00,67,00,65,00,20,00,43,00,61,00,72,00,64,00,5c,00,4d,00,69,00,6f,00,41,\
00,75,00,74,00,6f,00,52,00,75,00,6e,00,5c,00,53,00,79,00,73,00,74,00,65,00,\
6d,00,5c,00,45,00,78,00,74,00,72,00,61,00,5c,00,00,00,5c,00,53,00,74,00,6f,\
00,72,00,61,00,67,00,65,00,20,00,43,00,61,00,72,00,64,00,5c,00,4d,00,69,00,\
6f,00,41,00,75,00,74,00,6f,00,52,00,75,00,6e,00,5c,00,57,00,69,00,6e,00,64,\
00,6f,00,77,00,73,00,5c,00,43,00,6f,00,6e,00,74,00,72,00,6f,00,6c,00,20,00,\
50,00,61,00,6e,00,65,00,6c,00,5c,00,00,00,5c,00,4d,00,79,00,20,00,46,00,6c,\
00,61,00,73,00,68,00,20,00,44,00,69,00,73,00,6b,00,5c,00,4d,00,69,00,6f,00,\
41,00,75,00,74,00,6f,00,52,00,75,00,6e,00,5c,00,53,00,79,00,73,00,74,00,65,\
00,6d,00,5c,00,00,00,00,00
If this key is there, you definetely have a defect of Hardware.
BTW, when you unplug battery, you should also control plug of your Touchscreen, eventualy it is only a contact problem.