Greetings,
today there was a general network failure in our company and we pinpointed the error on RB750. All the LEDs are on (even though LAN cables are unplugged) and reset seems to have no effect (I hold reset button while powering on the device for few minutes without any help).
PWR LED is also on and that’s about it.
Is there any help to salvage and recover device or is it dead for good?
Thanks in advance!
I have had a one of these do this after a power outage. I was able to recover it with this.
http://wiki.mikrotik.com/wiki/Manual:Netinstall
I just reinstalled the firmware and it took off working again. If this does not work then I would say needs replaced but its worth a try. This process is not quick an may take 2 hours to complete so be patient.
Your answer might help me with a similar problem I am having. Thanks so much!! 
I’ve got a couple of RB750’s that will occasionally freeze up with all the LED’s lit solid but a reset will usually fix it. Kind of aggravating.
I have found this to be caused by ether1 of the RB750 being connected to an 802.3af POE switch.
Hi,
It could also be a capacitor (NOT solid state) problem. We have had three units that have been revived this way 
.
You can check on this post, there is even a slide show - http://forum.mikrotik.com/t/rb-750-problem-capacitor-fix/41306/2
Rgds,
Mark.
Wow, thanks, all, for your answers. I might be able to save some money on new routers thanks to you’all.
Jake