FRITZ!Fon C4 Service - Knowledge Base

FRITZ!Fon C4 Service
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FRITZ!Fon does not turn on

The FRITZ!Fon does not turn on. When you switch the telephone on, the message key and the end call key continuously glow red or only light up briefly. The display remains black and you cannot use the telephone.

Simply proceed as described below. After each measure, check whether the issue persists.

1 Recharging the telephone battery

The telephone cannot turn on if the battery is not charged enough:

  • Plug in the charging cradle. Make sure that you insert the plug of the charging cable all the way into the socket on the charging cradle.
  • Leave the telephone in the charging cradle for at least six hours to completely charge the telephone's battery. Make sure that the charging contacts on the bottom of the telephone rest on the contacts of the charging cradle.

2 Testing FRITZ!Fon with a different battery

The error could be caused by a defective battery. If you have an additional FRITZ!Fon C4, C5, M2 or MT-F, you can borrow its battery for testing purposes:

  1. Insert the fully-charged battery from another FRITZ!Fon into the telephone.
  2. Press the end call key on the telephone.

If the telephone turns on now, then the first battery was defective.

3 Replacing the rechargeable battery

You can purchase a genuine replacement battery from a specialized dealer. Using so-called aftermarket batteries that are not originals, like the kind available over the Internet, may damage your FRITZ!Fon.

Important:Rechargeable batteries wear out because they are subject to a natural aging process as physical and chemical changes occur within the battery; this is why they are not covered by the warranty (see warranty in the manual).