C3850 Fail to boot and can't load into RANMON mode

[Zenuncl]

I just got a device from my work which is a old used C3850. Trying to boot it but it failed.

I saw 2 different error multiple times during the boot, 

Error 1:

```

Booting...*** Address Error (Store) Exception ***

PC = 0x00000000 00000000

SP = 0xffffffff 80049670

Cause Reg = 0x00000000 40008014, Status Reg = 0x00000000 504000e7Booting...

```

Error 2:

```

*** Coprocessor Unusable Exception ***

PC = 0x00000000 00000000

SP = 0xffffffff 80049670

Cause Reg = 0x00000000 5000802c, Status Reg = 0x00000000 504000e7

```

Also try to boot into RANMON mode, by press the "MODE" button when plugin the power, but still can't load into RANMON or anything, either one of those above error will show in COM.

Is it hardware problem? Can I try to load it from USB to try to reinstall IOS to it? (USB, I mean plugin the USB and boot, without press any button or any other things, just directly boot to USB, can I?)

I am pretty sure it's out of warranty since it's a super old one and my company probably got it as used as well, so I don't expect I can get a replacement or something, but still trying to fix it myself. If it's hardware issue, can I replace the disk/storage/flash to fix it?

[marce1000]

  - FYI : https://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/ios-software-releases-121-mainline/7957-crashes-lesscommon.html#anc8
             In this case , I think this is a fatal hardware problem,

  M.

[Leo Laohoo]

Contact Cisco TAC and organize an RMA while it is still possible.