I've bought a used hAP ac² from local listing, and everything was fine for a few days after purchasing. I've done a complete configuration reset, upgraded it to 6.46beta28 and only set an admin password. Then I resetted it again after a day of tinkering (was fine after that) and put it back to the shelf for a day or two - it needed to wait for its actual deployment, replacing hAP ac lite at some location.
Then, after picking it back from the shelf (boxed) it couldn't boot anymore - the only sign of life is a lit "PWR" LED and ETH4 LED (but nothing has been put in ETH4 port yet).
- It doesn't react to any incoming traffic (at least on LEDs)
- It doesn't bring the carrier link up on cable plug on any of the ports
- It doesn't show up in NetInstall either
- It doesn't react to 30/30/30 reset
- …as well as 300s reset hold (for this task I broke off the reset button plastic cover on the case to get access to actual button and hold it with small lego brick and tape - and it doesn't broke the switch, it still "clicks")
I've opened it to check if some cap blowed up or broke, but it looks good and clean. I might try to plug a serial TX/RX connection onto board testpoints, but I'm not sure about yet unless there's no another option.
Any other way to determine it's alive? There's no info anywhere what the specific ETH4 light on boot mean, and warranty expired at 30.07.2019.