Toyotahead, I am also having exact same output when I tried upgrading firmware...no ubiquity/openwrt/dd-wrt just tp-link now the device just boots again and again..Serial console dumps output too...

Victor Ramos wrote just look at the label of 5210 and see the version of hardware you have to lower the firm Right... There you can see the process to restore a firm to a partially brick device, Hola...

Model : TL-WA5210G Hardware Version : v1 Firmware Version : was upgrading to 111209 ISP : So this happened 5-6 months ago and I tried updating firmware on my TL-WA5210G. I was not attentive and chose...

So I have TL-WA5210G with original firmware since I bought the product 3 years ago. So the router was kept unused for 1 year and now When I took it out this same symptoms are appearing. POWER LED...