In that case, the ATM was disconnected from the accounting system and allowed withdrawals up to a set limit ($2000), but it (probably, the article is unclear) was still connected to the authorization system.
It (probably) still checked your PIN, and checked whether your card had been cancelled, etc. It just didn't connect through to check your balance.
As Jeremy said if for some reason we can't reach the checking account system we'll authorize up to $xxx total for the day on a stand-in basis
In this case some reason == "[A technical problem]" and xxx == $2000
