sounds like an emergency so i’m surprised you’re not able to get anyone! boil hot water and cool it with cold water or mix the water from the shower with cold!
Boil water in the kettle, pour it in the sink and mix with cold water until required temperature
I second that!! Boil some hot water and add it into cold water, might need to do a few re-fills! Just make sure to swirl it around so there’s no hot spots, how old is your little one love? Usually if you let them know it’s been 24hrs without hot water and you’ve got a baby they’ll prioritise you xx
Use the water from the electric shower or like others said if you have a kettle or pot boil some water and put it in a bucket or something, whatever works and wait for it to cool or mix with cold water to cool it faster. Can still wash her in the sink like that.
Boil some water in a pot, and mix with cool water.