As I understand it the problem with lithium ion batteries exploding after being fully discharged is protected by their built-in circuitry. If it's totally dead it becomes dangerous to recharge but there's built-in circuitry that prevents recharging in that case. So if you've managed to recharge it it should be safe.
I'm no electrical engineer but I have read a bit about batteries and I've been using lithium ion for years in a lot of devices. So have my neighbors in my retirement home and I'm the one they come to with problems. Between them and me there have been a lot of forgotten devices that were brought back to life and never a fire.
That's not to say yours won't blow up your neighborhood tomorrow, but I think it's unlikely.
Barry