No cell signal after flashing ROM

I have a Jiayu S2 double-SIM phone, running the most up to date official ROM (4.4.2).

This ROM had a couple of bugs (no GPS and no notifications to external devices such as smartwatches), so I wanted to check other available ROMs. Using the Flash Tool I have tried a couple of the ROMs in the needrom site (https://www.needrom.com/category/jiayu/s2-jiayu/). In particular, a couple of versions of the official ROM, another ROM known as Salamander, and an unofficial port of Cyanogenmod 12 (in which the camera was not working).

The issue is that, for some reason, at some point my phone has stopped getting phone signal. The SIMs ask for the PIN on startup, but there is no signal. I have reverted to the original ROM; plus done a factory reset, and I could still not get signal.

The APNs for both SIMs are fine. Then I have realised that the IMEI was empty. Luckily I had it written down, so I have installed Xposed and the Device IMEI Changer, with which I have been able to restore the IMEI. Now I can see the IMEI on the Settings - IMEI information, as well as with *#06#.

But still, now with the original ROM, and with the IMEI restored, I still cannot get phone signal. I have tried setting the phone to flight mode, restarting, selecting manually the network... When trying to manually select the network I can see several networks, but the phone will simply not connect to the one it should.

Any idea on why could it be that I cannot get phone signal? Thanks.

 

After trying everything, including restoring the IMEI with Xposed, I have finally managed to restore cell service by restoring the IMEI with this tool: https://play.google.com/store/apps/details?id=com.cryptotel.chamelephon