Can't access settings or configure plugins (v3)

I installed a new website using Softaculous in my hosting account.

The first plugin I uploaded ‘all in one SEO’ I have not been able to configure, it is activated, but I receive the 503 message but funnily enough I have been able to activate and configure Akismet. I have also tried to configure ‘google xml sitemap’. Again it is activated but I receive the same 503 message.

I also can’t access ‘settings’ I receive the same message ‘503 server busy’. I have received this message for days now. I have used in the ‘updates’ the opportunity to ‘re-install automatically’ hoping this might solve the problem, but I am still unable to do any of the above. I have been into my cpanel to make sure the permissions are ok and they look the same as other wp sites I have, so could someone help me with this please?