It could be the diode on it is frazzled - the early ones used a diode that wasn't that good at high current - if the power lines ever got shorted then it'd (mostly) die and might power the chip but not much else. rev 1.4 added a self-resetting fuse to protect it.
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Ahh - is it one of the rev 1.3 Picos?
It could be the diode on it is frazzled - the early ones used a diode that wasn't that good at high current - if the power lines ever got shorted then it'd (mostly) die and might power the chip but not much else. rev 1.4 added a self-resetting fuse to protect it.
If you're not planning in using the VBAT pin then you can actually just short it out - or info on replacing it is on http://forum.espruino.com/conversations/281099/