Hi, I have exactly the same problem, did you manage to solve this problem?
I put in new seats from another Ram and still the same, so my seat heating mats are definitely OK. Only the driver's seat heating works, when I click the passenger seat heating on the screen, it automatically turns off after 3 seconds. The computer shows an error B2353-13
(right heated seats power supply-circuit open)
I don't know where to look anymore, the installation looks good.