Hello there!
My name is Nick and I will be happy to assist. Im a Senior Linux System Administrator and WHM/cPanel expert, I have been managing cPanel servers for the past 10 years and I can help you troubleshoot the booting issue from your server.
I dont think the crashing issue could be caused by the migration to EA4, this is probably something else. If your datacenter provides KVMoIP or some other sort of rescue mode I can attempt to troubleshoot this and fix it for you and make sure EA4 is active and running properly afterwards.
Im available now in chat if you have any questions.
Looking forward to hear from you soon.
Regards,
Nick.