I am having Error 500 in Paypal checkout. Coinpayment is also giving me this error(In picture below)

I bought a script and i have a lot of problems. Firstly i could not change the logo from the admin dashboard so i went over to change permissions of the folder and it kinda worked, Secondly, I had big issues with payment gateways, Coin payment is showing that error in the picture, Paypal is giving me the error 500 page when loading up. I need help please.