Hi @laminar31677
Here's the [https://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles_pdf/e520_e525_hmm_en_0a60536_05.pdf|hardware maintenance manual] for the laptop that shows how to open it and to remove most of the components.
It's not mentioned in the manual but if the Power button is faulty and needs to be replaced, search online for ''50.4MI06.001'' to find suppliers of the part that suit you best..
It is used in both the E520 and E525 models