Hardware reset/unbrick a 6D

[ubergeek801]

Greetings,

This is not a question specific to Magic Lantern, but this seems to be the place with the most hardware knowledge about Canon cameras outside of the manufacturer itself. So I guess it can't hurt to ask?

I acquired a secondhand 6D with an odd firmware version: "3-3.7.1 59(1c)". Not thinking much about it, I downloaded the stock 1.1.9 firmware and updated the camera. The update process proceeded normally, but when completed, the camera shut off and will not power on.

I have no idea what this mystery firmware might have been, but I can only surmise that it was accompanied by settings written to nonvolatile memory that renders stock firmware unbootable. So far I have tried removing the battery from the camera for about a week, and also removing what I presume is the backup battery from the backside of the motherboard, both to no avail.

As for what to do next, I am open to suggestions. In particular, I note that there are two flash chips on the motherboard; I have the means (a Raspberry Pi masquerading as a SPI flash programmer) to dump the contents of these chips from a second 6D and write to these chips. (Incidentally, one is a Winbond 25Q32DWSIG; the other is an MX25L6436E.)

Any advice would be welcome. Thanks in advance!

[names_are_hard]

That's a very strange looking firmware number.  How do you know it had that version?  It's a lot of numbers to remember - do you happen to have logs / photos showing the number?

Did you attempt to install ML at any point?  This may have saved a backup ROM that could be useful for recovery.

Most (all?) EOS DSLR have a serial port that can in some cases be used to reflash ROMs.  I don't know the location for the 6D, it may be on the forums somewhere already.

[ubergeek801]

I've acquired a number of these cameras for repair purposes, and I habitually check things like the firmware version and shutter count just to see what I'm dealing with. I didn't photograph the camera's display when checking the version, but I did record the output of gphoto2 when querying the camera via USB.

There are several connectors that look like they could be for UART/debug use; one of them is even accessible from the rear panel, underneath a rubber grip. I'll see if can dig up any information; thanks for the suggestion!

[Walter Schulz]

That's a very strange looking firmware number.

Looks like camera is/was in factory mode. See https://www.magiclantern.fm/forum/index.php?topic=15088.msg201244#msg201244
Updating a cam in factory mode should not do any harm AFAIK.

Tornado EOS has a feature enabling/disabling it in its payware version.

[ubergeek801]

Ahh yes, that firmware version certainly fits the pattern.

It might be worth a few bucks to disable the factory mode, but at this point it doesn't look like communication with the camera is possible through any normal channels (e.g. USB: the device won't enumerate at all).

[ubergeek801]

Also I neglected to answer: I had not attempted to install ML (although I was aware of its existence, my ultimate intent was to repair and resell this camera). I did attempt to use one of the diagnostic tools, on the off chance that the boot-from-SD flag had been enabled, but that doesn't seem to be the case either.

[Walter Schulz]

Basic procedure:

Remove battery, remove card. Insert battery and close compartment doors. Any LED activity?

Redo procedure with card:
Remove battery. Insert card. Close card compartment door. Insert battery. Close battery compartment doors. Any LED activity?

If nothing works: Make sure to have a working battery. You may need someone with a working camera running a compatible battery.

Are you willing to go the extra mile and try to access UART and log it?

[ubergeek801]

I've been through the drill a dozen times, although I must admit that I don't always notice the LED, falling at it does under one's thumb when holding the camera. Can't repeat it at the moment because the camera is in pieces.

I've also got about half a dozen other cameras around here that take LP-E6 batteries, so no shortage of those (Canon- and third-party-branded).

If I hadn't seen the camera operating normally (well, as normally as possible with a smashed reflex mirror) right up until the firmware update finished, I would have written it off as a hardware problem, but given the circumstances, it seems it's just being stubborn. So yeah, I think a little deeper prodding is in order.

Thanks!