Fenix 5x bricked

Something happened overnight after charging where my 5x seems bricked. At the time it was at 100% before I went to sleep.

After messing around a bit, I can tell the watch is attempting to do something up because if I press the LIGHT button for 30 seconds, then wait 5 seconds, then press LIGHT for say 3 seconds while the watch is connected to a battery pack, the battery pack displays that it is charging something, which stays on for a few minutes, then goes off (showing its not charging). So clearly something is happening when I press LIGHT. It "charges" for a few mins, then the battery pack goes dark. This is all I can make happen.

Green lights at the back don't illuminate at any time. No indication of startup happens (blue triangle or anything). If I try to hold the LIGHT button for 30 seconds while connected to a PC, then press LIGHT again to turn it on, nothing happens. I've cleaned the contacts, tried two different cables, no dice. 

I've tried LIGHT+START+BACK to wait for the beep with no results (how long does this normally take to get a beep? 30 secs, a minute?).

I haven't done anything stupid that would void the warranty like try to open it or anything.

Before I try and RMA this sucker, anyone have any advice?