Hi there
I have a similar (but not identical) problem from time to time on my Touch (Squeezebox Touch - display goes). It’s functional as I can use the screen to go through settings etc, but it was the screensaver (clock) that was not working.
I recently (yesterday!) fixed this by doing a power cycle and a firmware reinstall on the Touch (just through settings, it wasn’t an upgrade, just a rewrite). This hasn’t always worked for me, but I offer it as an option that may be worth investigating on your Transporter.
LK