Try misting your bird buy a new spray bottle from a dollar store and put warm water in it set the nozzle to spray a mist make sure you don't have it set to shoot a fine sharp stream as the sharp stream can scare your bird and its not comfortable if this hits them directly.
I put my budgie on top of the cage on a perch with a towel under him then I aim the bottle to spray up over his head and body then
quietly and slowly spray a shower of mist to rain down on him, he likes this a lot!
At first I had to practice and learn how to pump the handle/trigger of the bottle quietly and slowly as the sound of your hand pumping the trigger can spook your bird at first, the sound as well as the motion of your moving your hand quickly can make the bird nervous. So practice while standing at the sink until you have it figured out how to do this.
The mist is light and feels soft and warm on the bird so he will catch on soon what's happening and happily spread its wings and turn around to allow more mist to land on his body. Take your time when misting him talk to him and make happy encouraging sounds to make him excited so he enjoys the shower, talking to him while misting will help mask the sound of the pumping of the bottles handle as well!
If your bird enjoys to eat greens like lettuce or chard or spinach you can put some leaves in a shallow dish of water and leave it on top of the cage or where your bird like to hang out. I've gotten a bunch of my birds to bath by enticing them to reach into a water bath of veggie greens.
Also, you can just wet a bunch of leaves and leave them hung up in the cage or on top of the cage and allow the bird to wiggle and wash on the leaves. This is another option your bird might like doing to have a bath.