Amazon EC2: How to convert an existing PV AMI to HVM - CentOS - Wont boot

I've now tried every guide I've found on Google, some are posts on this forum. The instances always end up not booting with every guide/method I've tried. Probably spent about 4 days trying out different guides. I follow them to the greatest detail, never any errors. Only issue is when I'm done with the guides the instance wont boot. There is nothing logged inside "Get System Log".

I suspect that some special configuration has to be done to the bootloader that I'm not aware of.

These are the best guides that I've tried, none of them worked either:

Create an AWS HVM Linux AMI from an Existing Paravirtual Linux AMI

https://stackoverflow.com/questions/36427527/amazon-ec2-how-to-convert-an-existing-pv-ami-to-hvm-centos

https://www.caseylabs.com/convert-a-centos-pv-paravirtual-instance-to-hvm/

Ask me if there is any information you need me to provide, I'll do my best.

Any help would be greatly appreciated!

Sincerely, André