It is a communication problem between remote control and tankless unit
Temporary fix: 1 Turn off electricity to tankless and remove cover. Find two terminals that remote control connects to. 2 Disconnect remote control wiring. Turn electricity back ON. 3 Open hot water tap and see if unit works as expected. 4 Without remote, tankless will heat water to default 120 degrees F and will run without the remote. Contact Rheem they may send you another pcb board.
Answers & Comments
It is a communication problem between remote control and tankless unit
Temporary fix:
1 Turn off electricity to tankless and remove cover. Find two terminals that remote control connects to.
2 Disconnect remote control wiring. Turn electricity back ON.
3 Open hot water tap and see if unit works as expected.
4 Without remote, tankless will heat water to default 120 degrees F and will run without the remote.
Contact Rheem they may send you another pcb board.