I have the same issue with w760i check it the custmenu has any data

tpa/preset/system/custmenu

i did the same things as you and ended up with the same result. you phone is now not switching on is because the bat might be dead you will have to charge it externally but then u will still ahve the issue
read my post about w760i restarts it might help you. but it didnt help me.:( im still stuck with it.

what i discovered is what my custmenu folder is totally empty where as it should ahve some folders in it. I copied the same folder and data from a w910i to the w760i no such luck now im hunting for w760i custmenu adn hoping to try that out soon.. I will let you know if this is a success.;)