I believe 16ACE27 has the correct focus on this one. If the latching relay is “on” and won’t release then I would suspect the fuse that powers the door switch that operates or releases the latching relay first. If you have the RV Custom BCC (black box in the engine bay driver side; usually mounted near the inside cap front); the fuses for controlling the coach and chassis latch relays are inside the BCC. If you have the BIRD or BIM systems then I don’t know where the control switch fuse is located. A call to Thor may provide the likely location though.
If it is not the latch relay control switch power fuse, it could be the latch relay itself has failed in the on position. Using a voltmeter to monitor the control pin(s) on the latch relay would confirm if the on/off switch signal is getting to the relay.
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