Can't access WHM / cPanel

Hello there, I want to move from my current hosting to a VPS, I created an instance on Amazon Lightsail with the cPanel blueprint. Yesterday I moved all my sites and everything was working fine but today all the sites are down and I cant access to the WHM or cPanel. I tried to open a suppor ticket but the form asks me for the Support Access ID but I cant access to the WHM panel, I saw theres an option to get from the termnial but when l tried access the SSH terminal through the web browser Im getting this error message code UPSTREAM_ERROR [515] what can I do ? thx in advance