Working on the principle that if you owe the troika ?10m they own you, but if you owe them ?240bn then you own them, the new Greek government chose to call the troika's bluff.
Which is why the Greek debt crisis is now left permanently on the brink. The troika is now in so deep it can't afford a Greek default; nor can it risk a Greek exit (Grexit) from the euro in case other countries - Portugal and Italy are prime suspects - follow suit leaving the eurozone to collapse in a pile of worthless dominoes. But the Greeks are also in too deep to risk a default: were they to leave the euro and return to the drachma then the economy would become one of a third world nation.
...It's set up for a lose-lose situation, as no sooner does the troika pump in more cash, than the Greek people withdraw it. Better to have your cash under the mattress in euros, than leaving it in the bank where it could be turned into worthless drachmas at any moment. No matter who blinks first, everyone loses.