I can't see it if you posted a picture, but based on your description it might be scale insects. They typically hang on pretty tight and need to be removed by hand. They are pretty tough against sprays so you'd have to prune off heavily infested branches. You can rub them off where numbers are low. I've used rubbing alcohol as a spray for scale. It doesn't harm the plant. I've never done this on citrus, though, so someone else might have a better answer for you.

I don’t know why it would not post a pic to the post but here

Looks like scale to me. Rub them off or spray them. I'd keep the plant isolated from anything else you have so they don't spread. Tell your friend he has scale, too. He might have an infestation

Looks like you caught your infestation early though. Just keep rubbing them off, the branches shown don't look too far gone, but prune off anything that's obviously dead to help the tree recover. You could also use a good horticultural oil to smother them

Imhad them on my lemon tree, and they would never go away. I would clean them repeatedly and they would seem gone, and a fee months later they were back again. The tree never gave lemons once infected

You'll need to keep at it, there's eggs that won't be killed by the spray. You need to wait for those insects to hatch, then kill them before they lay eggs. It's the same process as treating head lice. You will get rid of them if you continue spraying even when they seem gone. You'll need to treat several times after you can't see the infection. Your lack of fruit is caused by the scale weakening the tree. Get rid of them and the tree will fruit

Spray with malathion as it kills on contact.

California Red Scale, or closely related species. See

https://idtools.org/id/citrus/pests/factsheet.php?name=California%20red%20scale

California red scale is an armored scale and will not be controlled well by malathion....it simply does not penetrate the hard outer shell. Can be effective on the eggs and in the crawler stage (before the scale becomes an adult and develops that hard outer shell) but the timing needs to be just right. And is a broad spectrum pesticide so will also kill off any beneficials or pollinators that might come in contact. And since it is an organophosphate (nerve disruptor), can be harmful to you as well if applied indoors or to any houseplant.