CECT C3100 Analysis
 CECT C3100
The CECT C3100 is a cheap MTK-based phone, retail price in China 120 RMB (ca. 18 USD). We bought 15 of them for 118 RMB each, shop said they buy for 115 RMB. Chips labeled on the PCB as: MT6223CA, MT6139BN, RDA6212+
 PCB disassembly
Gave a few boards to a PCB disassembly shop, paid 600 RMB (ca. 90 USD). Normally they take pictures then use some software to reverse the netlist. In this case we asked them to return the individual PCB layers to us, they sent the following pictures in advance.
According to initial (untested/unconfirmed) tracing of the PCB, the JTAG test pads look as follows: