Yes, it will be possible for sure.
1. try to reach the bootloder with the serial 3.3V adapter connected to the serial port
connect GND, 3.3V, Rx of NAS with Tx of adapter and vice versa.
If this works you can reflash the firmware. If not we go to step 2
2.Connect the JTAG signals with the FTDI adapter -
Link (Set the Jumper to 3.3V, connect GND, 3.3V, TCK, TMS, TDI, TDO)
With
NAS_Flashtool you can reflash the bootloader an then you go to step 1
I willl try to find some JTAG guide. Many links are dead unfortunately.
Maybe
this thread helps you although it is for a different board but the procedure is the same.
Merry Christmas,
HWguru