Very grateful to have received a reply. Much appreciated! I changed the cutter following the manual step by step, and there was a message that cutting has been successfully replaced. To be precise, the printer still printed well after changing, but the cutter did not cut well and I have to cut it manually. After this, problems surfaced. At first it kept rebooting, and now permanently displaying the error message.
The second video seems complex and have not attempted that yet.
Many thanks again!