Just adding myself to the message chain as I also would like to be able to run openvpn, but I don't really want to jump through all the hoops to compile kernels or the openvpn if it's all going to get broken by an Onion update. I would just rather opkg it and have it run :-)
Relatively unlikely to make a difference, by now that you've done the upgrade you might try booting it without the USB stick plugged in - it represents some additional load on the power circuitry, and adds some complexity of software possibilities.
Generally speaking there are three categories of things that could be wrong
You could have installed a bad image, or at least one that's wrong for the board. Always failing in the same place in the boot sequence would be a hint of this, but it would seemingly not occur with a different image especially one that previously worked.
You could have a power issue that's causing memory corruption rather than an immediate reboot. Always failing in a part o the boot process that involves wifi would be indicative of this
You could theoretically have a badly soldered board or one with bad components, not so bad that memory detection fails right away in U-Boot as has happened in a small number of cases, but more "flaky". However if a boad-level issue this would seem likely to cause more random failures than specific ones. An actual bad memory cell could cause a consistent failure but seems yet less likely.
@Chris-Stratton The problem is, that it does not reboot. It stucks with that message!
There's a chance the CPU did reset, but was unable to read the flash chip because on boot it would be sending 3-byte addresses while the flash chip may still be expecting 4-byte ones from the settings in use before the crash.