THL500 USB connection to pc help

Hi, i have a THL5000 with the following problem: usb connection to PC’s doesn’t work.
Although, charging from USB port works and USB OTG works.
But for some reason connecting the phone via usb cable to the pc won’t recognise the phone…

A sort history of phone mods and things I have done…
1. USB connection to pc worked fine with the original stock rom.
2. I rooted the phone with SP Flash Tools and installed a custom recovery and rom, again the USB connection to the PC worked just fine and everything else worked.
3. Afterwards I wanted to return to stock rom so I used SP Flash Tools and selected the option “Format All + Download”… everything went just fine, but when the phone rebooted the IMEI info were gone (rom working fine) and also I couldn’t connect via USB cable no more!

Charging the phone and USB OTG works fine, but I have tried connecting the phone to varius pc with varius os (linux, windows XP/Vista/7/10) but no PC recognizes the phone…
I have also tried downloading Android phone drivers to the PC’s but nothing, tried different usb cables and usb ports but nothing…
I have also tried using SP Flash Tools again but the pc doesn’t recognizes the phone so I’m stuck.

Any suggestions in fixing the mess I have made???