How do I diagnose and fix "No Service" on Samsung A52S A528B

I woke up one morning to find my mobile (it's pretty beat-up and recently had a professional screen replacement) displaying "No Service". I'm now unable to use mobile internet, make calls or texts. Other connections, WiFi, Bluetooth, etc. are working fine. Here's what I've done so far: - Check that the SIM works > I've visited my network provider and have got a replacement SIM. This has been check that it works in another functional phone. - Checked that the phone detects the SIM > *#06# in the dialer correctly shows the IMEI number and when I go to SIM Manager, it correctly shows my network provider. - Tried to manually select network provider, but when I try to deselected "Select automatically" I get a "Error while searching for networks" message. - Reset mobile network settings > no change. - Factory reset > no change. - Used *#0011# to show SIM info > HPLMN(234-30F) sim_state(0), No Service, Final IMEI Certi: PASS - Used *#9900# → run cp based log → copy to sdcard, then found the *internal storage/log folder/err folder/ss_log folder/MIPI_TEST.txt.* All devices were detected Present(0) - Used the Samsung Members Diagnostic tool to check all hardware - came back all OK. - Disassembled and inspected for loose connections and checked continuity of antenna cables (the white and blue ones). Reassembled and rechecked phone hardware - still "no service". I've been through just about every post on this and tried everything. No idea what to try next. I'm suspecting hardware failure. No idea what to replace. Antenna module? Charging port module? Motherboard? Any ideas?