Atmega328P burn bootloader with FTDI
You cannot upload the bootloader through the ATmega's UART pins.  

Perhaps the the necessary pins (SPI &amp; reset) are broken out on your board, and if not you may be able to tap them with some fine hookup wire long enough for the task as long as there are no conflicting peripherals connected to them which you cannot temporarily disable.

Otherwise you may just have to desolder the chip. 

A typical FTDI serial adapter is not the right tool for loading a bootloader either - it might at a stretch be adapted to very slowly toggling the ISP pins but the usual choices, such as an ISP programmer or another arduino with an ISP sketch on it will require far less effort on your part.