I have now managed to recover the phone but looks like only a clean install works dont try the option of retaining the apps and data using the home csc file as it didnt work for me and took me ages to recover the phone.
Thanks for the details there. I had hoped the home csc file would be ok but I'll stay clear. Not planning to try and recover the phone straight away anyway, new SIM will go in a phone THAT WORKS AND NOT A SAMSUNG, while I use the apps on the borked one until I can transfer them out. Some are security and a pain to have redone. But thanks for your pointer in the meantime! Appreciate it.
I have just reflashed the previous update (Android 15, one UI 7). Clean install. SIM card recognized ! I'm still watching if samsung releases a patch or anything...
I really hope they do a patched release as I don't want to have to bin the A53. I'm never going to use it as my main phone again but I hate to add to the recycle pile for no good reason.
Ok, good news: flashing with UI7 does not break the automatic update process. Bad news: it does not break the automatic process and Samsung did not stop pushing the buggy firmware to the devices. I did not find quickly where to disable it and I thought I have some time and would be asked to accept an update but now it takes place without a warning 😞
