Due to a mistake late in the day, the power off transistors for three LED groups are not working (T801-803). Solder 0 Ohm resistors there and disconnect the battery to power off the badge (otherwise, the LEDs are consuming 0.5 mA in stand by)
I've heard this happened with ~10 new devices, but mine also went black the next day (cxcv). This bug(?) appears on all devices at the same time but not all the time. on 2015-08-13 11:00 It worked, 2015-08-13 15:20 it went black again for the hackrf firmware. (f0086) Talked to the supporters, issue is related to power supply and they are working on a software fix (cxcv) Replacing the display fixed this for me (cxcv)
My display did also not show text. Sometimes other troubles as well and rad1o not really useable. Enabling VDD on RF (all the time) solved it temporarily. TX was too low and I found a bridge between VDD and RF1 below IC402. Resoldering it solved my issue. There should be no DC on the RF lines. Check DC voltages around the RF switches.
There is no high-pass filter populated (FL301) because of the cost. You can't transmit or receive above 2.75 GHz without modifications.