From what I researched the e-reader's motherboard contains three unused serial ports that can be connected from gps modules to bluetooth chips.
U2713 PIN OUT CLOSEUP
The article that gives instructions states that its hardware does not include a logic level to RS-232 voltage level translator("transceiver") so one must be added for RS-232 communications.
The board was apparently designed to use a connector similar to Digikey part number A99963TR-ND.
I don't know if a bluetooth chip has anything to do with the aforementioned sentence. Because this tutorial is meant for a gps module.
Based on this pin out and the board's design; if possible, what kind of bluetooth would I use preferably without wires to minimize hassle in soldering?