DIAGNOSIS Bitter, burnt taste is caused by baked-on coffee oils and residue in the internal hot water path, not just the basket or carafe.
FIX Run the specialized CLEAN cycle with a cleaning pod or vinegar, focusing on the internal tubes. Use a commercially available coffee maker cleaning pod (like Urnex) or the vinegar mix. Place a clean carafe under the head. Go to SETTINGS > CLEAN > CLEAN CYCLE. Start the cycle and let the entire reservoir run through. Follow with two rinse cycles using clean water only (use the DESCALING cycle for rinsing).
IF THAT DIDN'T WORK The charcoal water filter in the reservoir might be expired and imparting a taste. Replace the NWF1 water filter if it's been more than 2 months. Soak the new filter in cold water for 15 minutes before inserting it into the reservoir.
HEADS UP Never use dish soap or baking soda in the internal cleaning cycles. Use only products designed for coffee makers (citric acid-based cleaners, vinegar, or commercial pods) to avoid damaging internal seals and leaving sudsy residues.