I've seen a few reports of this, reason I've held off updating to 5.1
Are you actually feeling the device getting hotter? Apps shutting down etc?

Don't think you can in auto mode.

Your power controller is toast. There's a chip on the mobo (PM8941) that does voltage sensing, charge regulating etc... yours is totally broken. This is welded to the board so they will do a handset replacement. Should take around a week to do.
