@Wildthing - yes, and if you fire up the Rx it works, but nobody home on the control panel - I reset my SD card a couple of times, but it is possible the contents are not correct - my epiphany this evening is to dig out the most recent SD backup that was working and try that! I was grumpy I left it at work so it will be a job for the morning with a coffee!
The throttle and switch warnings are generic and you normally turn on/off at the control panel depending on your taste - Yes, possibly a 'safe' mode) - I will first try and work on the SD card with the bootloader, and if successful I will reinstate the programmed models from the OTX companion (on the Mac/PC).
There will be a solution - I am confident it is Software nor Hardware given the Bootloader screen and button work!
I noticed on the backed-up version the firmware is 2.3.2 (expecting SD card 2.3.18) and the SD card version is 2.3.18 - versus the current loaded SD card which has SD card version 2.3.20 - so it could be in the fine print (tomorrows another day)!