Failed radio (5E0035842A) - replacement options

The radio in my Octavia Mk3 has failed - for a couple of days it seemed to have a power issue and kept turning off before fully booted (power from USB port was also cutting so presumed power issue). After a couple of days it completely failed to turn on at all (no lights, and power through USB at all).

Have narrowed the fault down the head unit with some basic troubleshooting:

• Swapped fuses for radio and 12v supply - 12v supply working before and after swap, with radio not working before/after
• Pulled the head unit and screen out to check for loose connections and re-seat cables (all good connections)
• Used a multi-meter to check power in the cable block that connects to the head unit - good solid 12v going to the head unit

So it seems like the head unit and/or screen have failed (seems more likely to be head unit) but it is difficult to know what to look for in a replacement!

I want to fit a Skoda replacement, but I'm not sure what I should be looking for, so I have a few questions:

• My head unit is part number 5E0035842A and screen is part number 5E0919605B (images attached) - what are these known as? Bolero, Amundsen, Columbus? These are terms I read frequently on this forum but I'm not sure of the difference...
• What would people recommend as a replacement for the 5E0035842A head unit in an Octavia Mk3? I have an iPhone so would love CarPlay but not sure if that is possible, or affordable...
• Is there any security coding etc that will stop a simple plug and play install of a head unit sourced online e.g eBay? If there is security coding/pairing, is it a DIY job to get around it or dealer?

Thanks all - hoping to get some sound back in my car soon!