Curious, since the Qualcomm-based HTCs I'm familiar with don't complain if you set that cid value.
That is the so-called "super CID", which means that the phone has been modified more deeply than just flashing a ROM. The "cidnum" is the "customer id number", where customer means the carrier or region the phone was intended for rather than the individual who buys it. The "super cid" is a value that bypasses this check. This allows you to flash any RUU (ROM Upgrade Utility - a HTC package that completely reflashes the phone's firmware, not just the ROM but the bootloader, recovery, baseband and everything else) rather than just one intended for that cid. The downside is that if there are different hardware variants you could flash an RUU that's not fully compatible, so you need to be certain you know what model you have.
At least that's the way it normally works with HTC. I've no experience of MTK-based devices, which have some differences in how they work.
I presume you didn't make this modification, or else you'd know what the message means. Did your brother? Or did the phone have a previous owner? If the modification was made by a previous owner and you don't know what else they did that obviously increases the risk that you'll do something incompatible.
The SKU number in that screenshot should I think identify the hardware you have. I think, based on a Google search, that it's probably a single SIM model. If so then flashing anything intended for a dual sim model could cause problems. Is it possible that is what's wrong with your reception?
I'm afraid I've not tracked down an RUU for this device yet. It may be that some of these other tools/packages for MTK devices also replace the system firmware as well as the ROM, but I'm completely unfamiliar with those so don't know.
