No Wifi over 52%

Hello,

something really weird happens with my iPhone.

Last summer had a water damage with it. I had to replace some stuff to get it work again but everything went fine. After a while suddenly when my battery was over 52% i got no wifi signals anymore. After a reebot settings show "No wifi". When the battery drops under 52%, everything goes normal. Whats the part i should replace now? I have a new battery. Could that help? (i have to modify it a bit because i damaged something at the connector, thats why i would like to know what it most likely is).

Thank you

Johannes