If you’ve eliminated other possible reasons why your dishwasher isn’t drying, you can test the heating element. Simply run a Sanitize cycle and check that the Sanitize LED is on steady (not blinking). This can indicate it’s working. A blinking Sanitize LED may be a broken heating element.
You can also run a 1-Hour cycle or Quick Wash and select a Heat Dry setting. Once the cycle is complete, check that the dishware is warm. If it’s not warm, you may want to call a service professional.