The 'SwErr' message is actually indicating that the system thinks one of the panel switches is being held down! This could indicate that the contacts of a switch have stuck, even if the actual panel button seems to be up!
The '070B' in the warning is a code (in Hex) that represents the switch that it thinks is involved. However I have no idea which switch this is!
So I decided to check a few switches on my T4 by holding them down while entering the Test mode and recording the errors reported.
After a few attempts I found that '070B' was reported when the Metronome button was held down.
So it might be worth pressing the Metronome button a few (dozen?) times to see if you can free the contacts assuming that the problem is with this switch.
The switches on Tyros are individual tactile switches (not rubber strips like on the PSRs!). They can be replaced quite easily if necessary, but you need to be able to solder!
Even though you are getting the 'SwErr' message, you should still be able to carry out the tests in the Test program. The test that checks the switches is #023, but when you start it you must press the switches in the order given on the screen. You can't go straight to a specific switch. The Metronome button is the 21st in the check sequence.
This may not be your problem, but I would say that it must be worth a try!
Edit: I just tried turning on my T4 with the Metronome button held down and allowing it to boot normally, and it didn't produce the symptoms that you are experiencing - all panel lights worked as they should!
Regards
Ian