Need assistance with recovering a ZBT-WG3526

Installing and Using OpenWrt
1

I purchased a used ZBT-WG3526 recently and since it was already running OpenWRT Breaker Barrier, and was listed as being supported on the latest version of LEDE (17.01.4) I figured it was safe to just do a firmware upgrade through Luci to 17.01.4. Unfortunately it never came back after the firmware update attempt. Rebooting leaves it unresponsive. I found about the recovery mode(hold the reset button while powering on), and attempted to upload the firmware that way, but the download gets to 3% and then the web page goes unavailable.

I've tried the latest sysupgrade.bin for LEDE as well as an older OpenWRT, without success.
I also confirmed the Sha256 sum on the LEDE sysupgrade.bin file just to be sure.

Suggestions on next steps appreciated.

JD

2

Do you have the 16MB flash or 32MB flash variant of the WG3526?

3

There are no markings on the outside that say whether it is 16MB or 32MB. On the board it says ZBT-WG3526-SATA_V01.
There is a memory chip beside the heatsink(for the CPU) that is a NANYA NT5CB256M16CP-D1, but I think that is the RAM (4Gbit or 512MB?)
I have a photo of the board if that will help.

4

Seeing that there are two versions of the WG3526 in the ToH, my first thought is: Maybe you have a 32MB device (=snapshot support) and you flashed the 16MB firmware image (=17.01.4 support).

To replace any guesswork by knowledge, it would be a good idea to what's really inside, especially the flash chip. The NANYA chip you mentioned is indeed RAM.

And while you are looking at it, search for a serial port (most likely 4pins or holes in a row) and get the bootlog.

What is "latest"? 17.01.4 or snapshot?

5

Here's a photo of the board: https://photos.app.goo.gl/1sMq7iF8GwLvrwWW2. It looks like there is a serial port just above and to the right of the MAC address stickers.

Re "latest", I tried the 17.01.4 version of the 16M image.
I also just tried the snapshot of the 32M image. Same result.

6

Is this your router?

http://bit.ly/2htOGip

The pic of the board looks identical.

7

It certainly looks identical for a 16M flash and a 32M flash.

@jgdempsey What is the model number on the winbond chip?

8

More info...

https://wikidevi.com/wiki/ZBT_WG3526

9

Yes,except that it only has 4 antennas, not 6, but I think the missing two are the 3G antennas.

10

It's a 25Q128FVSG, which is a 128M bit, so it's 16M bytes..

11

Cool beans...you got it.

12

OK, now that we have figured out that it is in fact a ZBT-WG3526 16M, the next step would be to get the serial up and running and see what it spits out.

BTW: When updating from OpenWrt to LEDE 17.01.4: Did you check the "keep settings" checkbox or did you uncheck it?

13

Re the "keep settings" question.. I don't recall.. I may not have unchecked it.

I have most of the pieces to connect to the serial port, but I'll have to shop for a DB9 connector to connect to the usb - serial cable..

14

This is a good one to have on hand...

15

VCP drivers for the CP210x ...

https://www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers

16

Thanks for pointing this out.. I didn't realize that I would need a level converter (TTL to RS232). You saved me from frying something..

17

Would this do the job? https://www.kijiji.ca/v-networking-cables-and-connectors/ottawa/usb-to-rs232-ttl-uart-pl2303hx-usb-to-com-module-cable/1033768870 (something I can by locally tomorrow)

18

Or Maybe this one is better: https://www.buyapi.ca/product/usb-to-ttl-serial-cable-debug-console-cable-for-raspberry-pi/ because it will work with Windows 10 (not that I need it now, but may later)

19

Looks like both would work...don't use the red wire (VCC - 5.5v).

20

OK.. I've got a USB > TTL cable, and got the header installed on the board. I've played around with the speeds, but I'm not getting anything back from the unit besides a few dots.. If I send a "reset port" from the terminal program, I get a dot back from the router (and RX flashes)..
I've also tried monitoring it while attempting a recovery but nothing is output to the terminal..