Hi.
First, get ready to use the following keys: [ON], [E] and [C]. Procedure is as follows:
- press and hold [ON];
- while holding [ON] pressed, press and release [E];
- release [ON].
it starts a cyclic self test, with patterns and messages that should lead to a
[HP48SX OK! | | | ]
and start all over again. To stop it, you need a system halt (no memory clear with this procedure, only stack levels are cleared):
- press and hold [ON];
- while holding [ON] pressed, press and release [C];
- release [ON].
That should do. Do you believe a keyboard test is needed as well?
Cheers.
Luiz (Brazil)