i am facing exactly the same problem with the dim lights and everything, but with huawei echolife hg520b, i use a 12V 0.5 amp adaptor which is the original and i already made sure that its working fine , i also had the circuit scanned with this beeping machine , and what appeared to be the fault is a printed electronic component ,i think those cant be changed manually , i probably getting a new one as i am not really enthusiastic about sending it to get repaired, i wanna buy a new one and repair this myself coz they would probably take a fortune from me at the isp repair center