Flashing nordic n51802
I think it may be the nRF51802 or nRF51822 (you might have read the digits in the wrong order). Quite popular part. You can get the SDK, SoftDevices and all manuals from Nordic's website. SEGGER provides free Embedded Studio for Nordic chips.

You will also need a debug probe ("JTAG") to flash the device, for example a J-Link EDU or FTDI adapter + OpenOCD.