Invalid IMEI after factory reset After factory reset my phone starts showing "Invalid IMEI" on both sim slots and I can't call or be called. What might be the problem?

Android version; 2.2.1 , model: A601
If it has a Mediatek (which usually cleared IMEIs after flashing), you can try entering the IMEIs (found on the retail box) manually using *#*#3646633#*#*, and finding the option in Radio settings. I can't be sure if this works with newer MTK devices.