First of all, Thanks for your quick and comprehensive response.
We don't actually have a bricked Carambola here. And If I had, there is no problem with unsoldering the flash and re-soldering it.
This entire topic is regarding a product that we are developing, and where we want to make absoultely sure that whatever happens (including bit flips in the SPI flash), we can recover. If you deploy equipment in remote locations and require high reliability, this is not an uncommon situation at all.
In all non-consumer type deployments, cost of equipment outage, human labor to replace a device, logistics, etc. is all much more expensive than thinking
ahead and anticipating even worst-case situations. I have seen various flash chips (NOR and NAND) fail in the past, including much sooner than advertised by their manufacturers.
Another case to consider is a malicious attack. Let's assume an attacker gains root access to the device via some yet un-patched or 0-day Linux vulnerability. In a device with a single boot-source, without any way to recover automatically or fall back on another boot source he can permanently brick the device.
If 8devices had anticipated such in-system-recovery, I would have assumed that either
a) JTAG is available on regular solder-pads, available to the surrounding system/board, and/or
b) USB tools for recovery would be made available, and/or
c) the SPI flash be connected via a tri-state driver between AR9331 and flash, and/or
d) an option of booting from external SPI flash would be provided, e.g. by multiplexing the CS0 so the user could select internal/external SPI as boot device by toggling an external pin/pad of the module.
From what you are telling me, it seems like the Carambola2 is not capable of doing any of this, and we will more likely have to do our own board design with the AR9331 or another WiFi SoC, rather than the Carambola2
As we are buying the Carambola2 from 8devices and don't have a direct channel to Qualcomm/Atheros, we are not able to obtain the USB recovery program ourselves. However, as 8devices is buying AR9331, I presume you would be able to request this software via your support/contact. Could you please try this? It would be much appreciated. Thanks in advance.