Once you find the root cause after the removal of the HWH, please post your results and feel free to post pics as well. Might want to pickup some Butyl Putty Sealer Tape for re-installing the HWH..., may need it for the sealing the outer HWH frame against the outside TT wall.
Sometimes HWH removal can be a challenge...., been there, done it on my prior 2005 Eagle TT back in 2016. Make note of wire color coding and associated connections (take reference pics).
Here's my HWH R&R project, with pics:
2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (Strait-Line)