The ABS controller has detected a problem, and disabled the entire system. The only way to know what is wrong is to get the system scanned for codes. Trying to lock up the tires to find the one that hs a bad sensor is not going to work. The whole ABS system is shut down. The regular brakes are fine, and the tires will lock up. The ABS system will not kick in to prevent the tires from locking up.
The ABS system is more than just wheel sensors. For this problem, don’t start replacing parts hoping to hit the right problem. It will get expensive quick. Get the codes read. I cannot stress that any more strongly.