Red screen updating CX CAS to 4.5

I installed nloader to install CAS on my CX (non-CAS) a few years ago, and updated to 4.0.3.93 too, with ndless.
Today I followed this guide to try to update my calculator to 4.5.4.48: viewtopic.php?f=57&t=22530 and viewtopic.php?f=57&t=18920#updatecx
It updated (or installed controlx) on the diags partition, then I deleted the 4.0 OS by the manuf mode and installed the 4.5 CAS OS. However, on rebooting, it goes to that "Your calculator has been modified to enable CAS functionality" screen and after booting the OS, it goes to a red screen. I tried to erase the OS again and try to flash 4.0.3.93 back but it won't let me downgrade the OS, as the minimum version is now 4.5.
I tried following other guides, however Ctrl+Menu+Minus doesn't seem to do anything on boot...
Any way to unbrick my calculator?
Today I followed this guide to try to update my calculator to 4.5.4.48: viewtopic.php?f=57&t=22530 and viewtopic.php?f=57&t=18920#updatecx
It updated (or installed controlx) on the diags partition, then I deleted the 4.0 OS by the manuf mode and installed the 4.5 CAS OS. However, on rebooting, it goes to that "Your calculator has been modified to enable CAS functionality" screen and after booting the OS, it goes to a red screen. I tried to erase the OS again and try to flash 4.0.3.93 back but it won't let me downgrade the OS, as the minimum version is now 4.5.
I tried following other guides, however Ctrl+Menu+Minus doesn't seem to do anything on boot...
Any way to unbrick my calculator?