Google finds posts like this (in German) - does the device still contain the bootloader it ships with ?
https://www.mikrocontroller.net/topic/94307
There several ways of loading the flash of LPC9xx micro controllers:
- In some parts, parallel programming. Option not available for OP as the IC is soldered to the board, and the particular part OP has may not even support it.
- In some parts, In-System Programming (ISP). This is done via the serial port and a bootloader. Although possible in the LPC9361 assuming the bootloader had not been erased, is also not available to OP as the serial port pins are probably not available.
- In all parts, In-Circuit Programming (ICP). This is done via dedicated pins in the IC. This is the only option available to OP as the ICP pins are the ones provided in the board.