first alternative is, that you get console access to your TV as described here.
If for whatever reason, you don't manage to get console access, then I think the next step would be to give a try via the bootloader ( holding "~" during bootup etc. ) and alter flash directly via the bootloader ... this I have not done myself yet though. Let's first try above alternative
Regards
dynamic
EDIT: Are you still able to enter the Service Menu ? If so, can you check whether you also have a "WATCHDOG" setting, that you can disable ?
If so, then please disable that setting for the time being, until you have fixed your FW. This would prevent your TV from automatically rebooting if exeDSP is not running.