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RB751U semi bricked

Posted: Sun Jan 05, 2014 7:36 pm
by duvi
Dear all,

after an unsuccessful attempt to try installing Openwrt on this device, I'd like to put back RouterOS with Netinstall.
The problem here is that to be able to install Openwrt, I modified the boot protocol from BOOTP to DHCP from inside Routeros, but Netinstall only works with BOOTP (at least it doesn't detect the device - I see DHCP requests from the router, but netinstall replies BOOTP, which the rb751 doesn't accept, and keeps requesting dhcp). But I can't set back the boot protocol to BOOTP since RouterOS is already gone from the device...

What do I do now?

Thanks!

Re: RB751U semi bricked

Posted: Mon Jan 06, 2014 9:27 am
by normis
When you use the reset button on the device, before applying power, it makes the device load the backup bootloader, with the default settings.

Re: RB751U semi bricked

Posted: Mon Jan 06, 2014 1:58 pm
by duvi
And what are the exact steps to achieve this?
I tried releasing reset button right after I plug the power, or waited until ACT led stops blinking, but the router still waits for a DHCP response, not BOOTP.

Re: RB751U semi bricked

Posted: Mon Jan 06, 2014 2:00 pm
by normis
The only requirement is to push the button before applying power. If this isn't helping, you really managed to brick it, because the unit has no serial port, it will not be possible to upload a new FWF file. Check if you still have warranty for it, we will fix it, if you do.

Re: RB751U semi bricked

Posted: Mon Jan 06, 2014 2:12 pm
by duvi
But it isn't bricked, because I see DHCP requests coming from it, and I can send e.g. an openwrt ramdisk image to it with tftpd32, and that boots.
What I need is it to communicate with Netinstall, not tftpd32.

Re: RB751U semi bricked

Posted: Mon Jan 06, 2014 2:14 pm
by normis
You already described why it's not possible, and I can't see any alternatives. Warranty repair service has possibility to reprogram the board in other ways, which is not possible for you to do yourself, so this is the only option.

Re: RB751U semi bricked

Posted: Mon Jan 06, 2014 5:55 pm
by duvi
Thanks, I actually ended up installing openwrt.
Maybe Mikrotik could try to solve this "Catch 22" somehow (: since the router is not bricked, it's just impossible to put RouterOS back..
Adding DHCP server capabilities to Netinstall could be a solution.

Re: RB751U semi bricked

Posted: Tue Jan 07, 2014 9:34 am
by normis
It looks like the device that you have, doesn't support reset of RouterBOOT via button, but only via pinhole reset. Look for a reset jumper hole under the case, use a philips screwdriver to short it, then apply power, and it will reset the RouterBOOT settings (which you changed in RouterOS before)

Re: RB751U semi bricked

Posted: Wed Jan 08, 2014 5:43 am
by randomguy
Out of curiosity, what is this reset labeled as on the board. I see a number of spots for pogo pins which is i'm guessing for reprogramming the NAND. I'm in a similar boat and would much rather take care of this myself.

Re: RB751U semi bricked

Posted: Wed Jan 08, 2014 9:05 am
by normis
Out of curiosity, what is this reset labeled as on the board. I see a number of spots for pogo pins which is i'm guessing for reprogramming the NAND. I'm in a similar boat and would much rather take care of this myself.
Depends on the device. Here is how it looks like on all devices (section "jumper hole reset")
http://wiki.mikrotik.com/wiki/Manual:Password_reset