Shame i didn't took pictures when i done it. This is surprisingly super simple to do. Just take a picture of how the battery is connected to avoid to invert the positive and the negative. You just have to remove the rubber, and disconnect the battery. When you change it, or you solder it like...

Hello, few months ago i had to change the battery of my fiio, i used this one. It fit perfectly, you just need to move from the old battery the circuit who is up to it...

I am not sure of it but it is warmer than usual so i think it should use more, i will do the test

I tried the 3 of them and all are working very well and with the medium one mine is already smooth.

Hello, i have the x5 rd, how can i know which is the kernel (mhz rapidity) best version for my fiio ?

Thanks a LOT for your help !!! it resolved my problem and now i can enjoy this new kernel and give a new life to my Fiio !

Thanks for your answer, but how can i install twrp in my fiio from a mac ?

Hi, i heard a lot of good things about your Kernel, i am trying to install it in my X5rd from my mac but this is crazy complicated for me. Does exist a tutorial who could help me to enjoy it ?