Simple answer is. You can't

There is no way to go back Online now.😥

you can still download online and create an account,

but that i know of no way to move your cards back.

I have re-started online for the time being and bought my favourite deck back on there to play especially while this lates bug is around. luckily my deck wasnt an expensive one to get hold of on ebay for less that £10.

I hate Pokémon now I lost $100s migrating it is so stupid. They need to make it to be able to migrate back to pokemon tcgo.