I wrapped up a build, which was working fine for a while, but i left it on just playing its screensaver game samples and came back a little while later and the screen was off (i think the low bat light was on on the psu as well). recylcing the power and recharging did nothing to bring it back up - it looked like the pi and other accessories were turning on, but the screen wouldn't come back (great

i just opened it back up to poke around, and now it seems like instead of getting 5v at my power, I'm only getting ~3v from the power supply. i'm running an adafruit powerboost 1000c and i have an adc and cambles shutdown in there as well, and i can post some pictures if someone wants to see it, but i think the wiring is ok, since it was working fine before. i can plug it into a wall adpater and/or just the battery, and it doesn't seem to "boost" any more.
i think, maybe leaving it on until the battery drained too much might have forked up the powerboost... ? or maybe it just went bad or something? the battery i was using was just an inexpensive flatpack thing, but it appears to have its safety cicuit and seemed ok when i was testing.
any thoughts or suggestions? i don't really have any other powerboosts around (i think i have a 500, not "c")