i had the same problem a week or two ago, i was tethering with barnacle, and suddenly my connection was lost (my phone was charging in my laptop)...
when i checked my xperia (i was downloading stuff so i was tethering for something like 4-5 hours) the device was very hot and with the same probles previouly described (blinking in red, not turning on, etc)....
i was very scared, waited for a while until the temperature was cooler and the i plugged to the wall for an hour or so... without an answer, suddenly the charge icon appeared (phone turned off)... and it got in perfect shape again...
the other day i was using barnacle again and i looked at the phone (charging with my laptop again) and i discovered that it was again draining even when charging so i decided to charge in the wall and it was ok...