With the ping method, all packet say "Destination host unreachable".
Including a continuous ping at router power-up? It's always good to have a USB serial adapter around if you're gonna use third-party f/w, but it sounds dead to me; and possibly not even reasonably recoverable. Unless you can open it and check/change caps yourself, it's probably best to search thrift shops, ebay, craigslist/facebook/similar for something rather than pay to have yours evaluated and (possibly) repaired at a shop. I've found some amazing deals at Goodwill in the US.
I opened the router and here is the motherboard inside.
Hmm...is that input cap (large cap near the power connector) bulged and (barely) leaking? What is the value and voltage? _________________ #NAT/SFE/CTF: limited speed w/ DD#Repeater issues#DD-WRT info: FAQ, Builds, Types, Modes, Changes, Demo#
OPNsense x64 5050e ITX|DD: DIR-810L, 2*EA6900@1GHz, R6300v1, RT-N66U@663, WNDR4000@533, E1500@353,
WRT54G{Lv1.1,Sv6}@250|FreshTomato: F7D8302@532|OpenWRT: F9K1119v1, RT-ACRH13, R6220, WNDR3700v4
Hmm...is that input cap (large cap near the power connector) bulged and (barely) leaking? What is the value and voltage?
I'm not sure. The images from FCC also show the same. Link
How do I determine those value?
The FCC pic shows no bulging nor leak. On the side of the cap it show the capacitance and voltage. E.g. '330uF 16V' _________________ #NAT/SFE/CTF: limited speed w/ DD#Repeater issues#DD-WRT info: FAQ, Builds, Types, Modes, Changes, Demo#
OPNsense x64 5050e ITX|DD: DIR-810L, 2*EA6900@1GHz, R6300v1, RT-N66U@663, WNDR4000@533, E1500@353,
WRT54G{Lv1.1,Sv6}@250|FreshTomato: F7D8302@532|OpenWRT: F9K1119v1, RT-ACRH13, R6220, WNDR3700v4
It's Su'scon 470uF 25V. The other two are Su'scon 470uF 10V. I'm not sure if the green mark is the leak or not.
The green is a quality check marker. The little brown dot is a leak though; and ya that cap is bulging. First visibly failed cap I've seen on a router...congrats. No idea if replacing it would help your issue, but definitely wouldn't hurt. Just don't use less than a 470uF 25v to replace it (it's just a power input buffering cap to the voltage regulator, so higher values are fine). If it were me, I'd use a pair of my 330's in parallel to make a 660 (since I have a ton of them). _________________ #NAT/SFE/CTF: limited speed w/ DD#Repeater issues#DD-WRT info: FAQ, Builds, Types, Modes, Changes, Demo#
OPNsense x64 5050e ITX|DD: DIR-810L, 2*EA6900@1GHz, R6300v1, RT-N66U@663, WNDR4000@533, E1500@353,
WRT54G{Lv1.1,Sv6}@250|FreshTomato: F7D8302@532|OpenWRT: F9K1119v1, RT-ACRH13, R6220, WNDR3700v4
I also didn't check any of the links, but that thread is the one that came up when I Googled debricking and serial recovery for this device. Replacing the cap shouldn't be too difficult, and it may not even require de-brick or serial recovery afterwards, but now you have what you need in case.