Been years but IIRC press "display" button on hand unit.
Without the right unit it probably is stuck.
Also IIRC this set-up was only used a few years & you cant do a lot
such as channel setup without the right remote. All the remotes were
subbed to a monster remote that went for $80 ! To get the ORIGINAL
find the "RM###" number & look on E-Bay. Number is on old one
& in service manual.
73 Zeno
LFOD !