NBv4 dim LED when powered off

My Nano Biscotte with Power Xtender and RGB XP-E2 CopperNova has been working fine for months.
Today, I charged it via the charge port as normal. Soon as the charge plug (or kill plug) is removed, a bright red flash, followed by a dim red LED is on all the time. (This is true with or without SD card in place.) The voltage at the red LED is 1.777V. When powered on, everything works properly with the exception that the red LED is on a little bit at all times. When I choose a sound font with red, the red LED does go to full power as it should.

I checked all of the solder joints and wiring insulation. It all looks good. I see no evidence of any burn marks on the Nano Biscotte. My guess is something is fried on the Nano Biscotte (or power xtender) because if it was a solder or insulation issue, the red LED wouldn't flash full bright when powering up. That is not normal.

Any suggestions?