Five formats, one manufacturer, and no label telling you which is which.

Fujitsu and Fujitsu-Siemens laptops (Lifebook, Amilo, Esprimo) lock in five different ways. Paste what your screen shows and all five are tried.

The five formats

Count the characters first, then check whether any of them are letters. That is enough to place almost every code.

On screen	Example	Which scheme
8 hexadecimal characters	`DEADBEEF`	Plain hex
20 hexadecimal characters, often five groups of four	`AAAA-BBBB-CCCC-DEAD-BEEF`	Hex with a model prefix, only the last 8 matter
20 digits, no letters	`1234-4321-1234-4321-1234`	One of two decimal schemes, old or new
24 characters: 4 hex, then 20 digits	`8F16-1234-4321-1234-4321-1234`	Decimal with a model prefix
24 characters beginning `203c-d001`	`203c-d001-0000-001d-e960-227d`	The `203c` format

Telling the lookalikes apart

Two pairs cause almost all the confusion here, and one of them cannot be resolved from the code at all.

8 hex versus 20 hex. These are the same scheme. The 20 character form simply has 12 characters of model identifier in front of the 8 that matter, so both produce the same answer, if you have the long one, you have not got a different lock.
Old versus new 20 digit decimal. These genuinely are different schemes, and nothing printed on screen distinguishes them: the difference lives in a byte-swapping step inside the firmware, not in the code it shows you. A 20 digit code therefore gets you two candidates, one from each. That is not the tool hedging: it is the honest state of what can be known from the code alone.

Dashes and spacing mean nothing. Fujitsu's own screens group these codes in fours for readability and different models group them differently. Type it however it appears; the grouping is stripped before anything is computed.

Entering the code

Take the answer back to the locked machine and type it at the same prompt, then press Enter. Several of these formats return an answer containing letters, type them as shown, case does not matter. If the machine drops you into setup, it worked.

Clear or change the password while you are in there, and reboot to confirm it is gone.

If it did not work

Re-read the code. On the hex formats a misread B for an 8 is easy and fatal. This is by far the most common cause.
Try every candidate. A 20 digit code legitimately produces two, and only one of them is right for your firmware.
Check you copied the whole thing. The 20 and 24 character formats are long enough that a group at the end gets dropped surprisingly often.
Some machines want a reboot between attempts. Power-cycle and fail the password again to get a fresh prompt.

One thing people ask

Is using this legal? On a machine you own, yes: it is your firmware and your password. We ask the same of you here as we do of paying customers, use it on your own laptop. It is not a way into somebody else's.

Wrote a code.txt instead? Start recovery.