Well it could be said that you have a battle of wills ahead of you to deal with the behaviour issue that he is not staying in his bed.
Climbing out of the cot is exactly the same behaviour issue. So you would deal with it in exactly the same way you are going to have to with the bed.
Plus you get the added benefit of the security cot sides being a toddler. Plus it being over-all safer for the toddler to be in the cot rather than a bed, once The Rules (ie lying quiet at sleep time) are established. Plus you get no extra problem of messing around in bedroom when it should be sleep time.
But if you don't feel you can go back to the Cit, I would deal with it by use of Rapid Return and a behaviour expectations mantra.
The instant child even so much as sits up, certainly if they get out of bed, you get to then as quickly as possible and immediately return to lying down in bed.
Little interaction in this return aside from repeating the mantra. Some thing like "we lie down quietly to sleep. It's sleep time now, Nan night".
Every shout. Every movement. Quickly return to then, repeat mantra, leave. Repeat repeat repeat until they eventually accept The Rules.
(You could deal with cot climbing in exactly the same way)