PIC 12F509 begins to heat at power up

[ErnieM]

Same old code, same chip, new batch of boards.
Check for a bad trace.

OR... new revision silicon is acting up (doubtful).

Interesting problem, current is going somewhere, but current isn't a directly measurable quantity suck as voltage is. Good news is you only have 6 I/O pins to check.

Depending on how repeatable the problem and how disposable a board is you could try removing one pin at a time to see who the current hog is, then seeing if you can switch on the big current if you put the offending pin back in.

One thing to check is if an INPUT is causing the problem: if an input goes to about half Vdd then it will draw a big current (thru Vdd->Vss, not the pin itself).