Climbing onto tables and turning on xbox constantly...

[5 Little Monkeys]

I wouldn't feel bad about putting him into his highchair so that you can safely change diapers and make meals. It keeps him safe!

Do you have a toy shelf (or something similar) that you could pull in front of the entertainment centre to block it during dc hours? Could you use velcro and attach a curtain during dc hours to cover the centre...out of sight out of mind?

Constant direction, reminders and being firm will hopefully help!