Need help with Error: VC31 WHO_AM_I failed (0)

I see the same issue, and following the above steps:

This doesn't sound good - can you locate where is the heat is coming
from?

Centre of the watch, roughly where the HRM is, I'd guess

The first step I'd suggest is to ensure you run the battery totally
flat (there's a menu option in Settings for this) and leave it for an
hour, then recharge.

Done, ran the battery down, left it for a day. Same issue - when HRM fires up the watch heats up and the green HRM light never appears. Battery consumption then goes through the roof, even if HRM is turned off.

Are there other steps I can take, such as dismantling the watch to see if there's any loose components?