HX FX Stuck in Boot Loop

[areabassist]

HX FX came up with blank LCDs (backlit, but blank). Still connects to HX Edit and shows patch info. I reseated ribbon cables (the main one had been disconnected) but that did not fix it. I forced Update Mode and successfully updated to the latest version using Line6 Updater. It's still stuck in a loop when I try to boot it up - about every 10 seconds I can hear the relays clicking. These are down to $500 new so I'm not sure it's worth taking to a shop at $120/hr labor plus a board or whatever. 

 

Any suggestions?

[areabassist]

Also - I'm using the original power supply, and also tried a 1 spot (1700 ma) with no luck

[Schmalle]

Now that you've excluded the power supply from the list of possible causes two things come to mind that you can give a try:

1) You mentioned you reseated the "main" ribbon cable. The HX Effects actually contains two primary ribbon cables:  
 

The wide main ribbon cable connecting the main processor board to the display/footswitch board.

A smaller, secondary ribbon cable that specifically routes power and control data to the upper scribble strip/LCD assembly.

If the main processor tries to boot, queries the secondary display board, and receives a short circuit or no response due to a bad connection, the bootloader will crash and force a reset loop.

Open it back up. Disconnect both ribbon cables. Clean the gold contact fingers on the ends of the cables using 99% Isopropyl Alcohol and a Q-tip. Ensure they are seated absolutely straight and deeply into their Molex plastic collars before locking them down.

 

2) Because you just did an update while the unit was in a semi-broken state, it is possible there is a corrupted global settings file or "problem preset" causing a boot crash.

Even with blank screens, you can force a hardware reset using the physical switches:

Turn the unit OFF.

Press and hold Footswitch 6 (top right switch) and the TAP switch simultaneously.

Turn the unit ON while holding those down. Keep holding them for about 10-15 seconds.

If it successfully clears the state, the boot loop might stop, allowing the displays to spring back to life.

 

Good luck finding the cause of the issue, share if you find it.