Went out to start my 2008 Lexus 350 RX this morning and the heat wasn’t working. Let it run idle for ~20 minutes, still no heat.

Checked the coolant and it is frozen solid. It is around 20 degrees right now and won’t be above freezing until around 4pm today.

I ordered some appropriate coolant to be delivered to me in a few hours. Other than just adding some of the new coolant, what can I do?

I was in a fender bender about a month ago but the heat has been working fine since then. No visible damage to the coolant reservoir or anything nearby.