Can't able to see ACCESS POINT(failed at rebooot)

Hello There,
I'm a novice in this hardware things,
i have oneWWRTnode2R_DB_v1.2, on powerup in cant see access point of this hardware.
i have connected this board using USB to TTL, so I'm able to see the device is stuck at reboot having following errors

[   15.652943] Stack : 00000000 80060e30 000000f5 00000000 00000381 8036dbf4 00000000 00000001
          8036dbf4 00008000 00001c06 80036284 803c0000 00000000 00000000 8006130c
          80370000 801a5440 aaaaaaaa 8031cb1c 00000000 00000000 00000000 00007ffe
          00000000 00000001 80361968 00000007 00014600 802fac88 802facb0 00000001
          80360000 8004bf0c aaaaaaaa aaaaaaaa aaaaaaaa aaaaaaaa ffffffff 7fffffff
          ...
[   15.687215] Call Trace:[<80060e30>] 0x80060e30
[   15.691504] [<80036284>] 0x80036284
[   15.694863] [<8006130c>] 0x8006130c
[   15.698224] [<801a5440>] 0x801a5440
[   15.701585] [<8004bf0c>] 0x8004bf0c
[   15.704946] [<8004f2fc>] 0x8004f2fc
[   15.708303] [<8004b7fc>] 0x8004b7fc
[   15.711664] [<80011868>] 0x80011868
[   15.715024] [<800047f8>] 0x800047f8
[   15.718382] [<80060e30>] 0x80060e30
[   15.721747] [<8016bca8>] 0x8016bca8
[   15.725104] [<800047f8>] 0x800047f8
[   15.728464] [<80027424>] 0x80027424
[   15.731823] [<8004f2fc>] 0x8004f2fc
[   15.735185] [<800047f8>] 0x800047f8
[   15.738539]
[   15.739967]
Code: 24849b48  24020001  a202cb6b <8e220080> 7c420400  10400018  3a740001  8f840000  8c82000c
[   15.749591] ---[ end trace 93ee691b00000000 ]---
[   15.754001] Kernel panic - not syncing: Fatal exception in interrupt
[   15.760132] Rebooting in 1 seconds..
[   15.763674] Reboot failed -- System halted

don't know how this board work. i have to insert os on SD card?
is it working like raspberry pi??, unable to find proper documentation of getting started.
don't know what is an issue?
is there any guide so that I can flash firmware and bootloader and can fix this?
any help appreciated
Thanks.