I have a MR 18, firmware 25.9. So I used method C, as described in the WiKi devi for MR18. I cannot post the URL link here.

Now I connect the USB-serial and using putty I see very fast scrolling garbage and I cannot stop it. I downloaded Hyperteminal for Windows and that shows the same, but I was able to stop the scrolling of the screen.

I see this:

Meraki Atheros LinuxLoader MR18 built Jan 31 2014 15:53:22
qca955x_init_ddr ok
test_memoryfailed RAM BORKED: (0xa0000000) 0x5a5a5a5a != 0x0
error booting
__________________sri____________________
944x BootROM Ver. (asic) 1.0 [Nov  8 2011 13:42:57]
_________________________________________
find_hif: bootstrap = 0x31459
Nand Flash init
hdr: [0xbd000400 : 0xbd000400 : 0x6fb4 : 0xe5c86b84]
nand_load_fw: read 13 pages
nand_load_fw: 0x10000 0x800 0xbd000bf0
nand_load_fw: 0x20000 0x800 0xbd0013f0
nand_load_fw: 0x30000 0x800 0xbd001bf0
nand_load_fw: 0x40000 0x800 0xbd0023f0
nand_load_fw: 0x50000 0x800 0xbd002bf0
nand_load_fw: 0x60000 0x800 0xbd0033f0
nand_load_fw: 0x70000 0x800 0xbd003bf0
nand_load_fw: 0x80000 0x800 0xbd0043f0
nand_load_fw: 0x90000 0x800 0xbd004bf0

What does that mean? Is it "dead"? How to revive it? Anyone seen this? Especially the bold highlighted sentence.

But when I disconnect everything, and boot up the Meraki AP as intended (original firmware), then it comes up in the Meraki dashboard. So the device works!

I also met the same case as you, I also need detailed instructions

A friend of mine who does a lot of programming, said, that the RAM BORKED message means, that the Cisco AP found out that there is a "fake" UART connected, and blocks it's memory. That is because I used a "cheap" Chinese UART USB converter.

The USB converter should really have an independent CP2102 chipset.

The USB converters which are sourced locally, should work. Today or tomorrow the new USB converter will arrive. I will try again and let you know.

OK, I managed to get it done.

It turns out that you cannot interrupt the boot process by holding 2. The time the USB port needs to be accepted by Windows once inserted, takes too much time. In that time the MR18 is already booted.

Unless you have a REAL RS232 (9 pins) on the back of the computer (I have one on my docking station), then it might work.

In any case, the manual says that the firmware should be uploaded into "part 2"  of the NAND. That did not work because of the late interrupt (see above). So I installed into "part 1". After reboot, I got immediately the LEDE prompt. After that the device was reachable at 192.168.1.1, and the GUI was working. So after that 5 minutes of work (new firmware, reboot etc...) it works like a charm.

(Last edited by haik01 on 7 Mar 2018, 23:05)