I have an old Powerbook G4 and can't get it to start up to get the serial number. How do I find it?

PowerBook G4s came in Aluminum, 12-inch 15-inch 17-inch ~ or Titanium (15-inch)

there are subtle differences among 'non-functional' PB G4 models to identify builds.

In some there are different locations; one of those may be inside the battery bay.

Remove battery: serial number should be on sticker inside the PowerBook..

..Another place, may be outside the PowerBook along the back hinge area.

Tiny print; sales order/model number may be in this location; if no serial number.

You may be able to look up the build model year by sales order, model number

or several 'non-serial' number identifiers. Everymac ultimate lookup is a resource.

Powerbookmedic has lookup page, too; shared with their parts site.

Differences in: materials, display size, CPU/GPU specs; help identify in PB Medic site

• Powerbook G4 Titanium Model #s and Speeds (all 15-inch display)

• Powerbook G4 Model #s and Speeds (aluminum 12-,15-,17-inch) Pb_medic

PB Medic site also has repair guide pages, unlike ifixit's or apple's.

There could be additional details I've forgotten; I've owned most.

• Apple PowerBook G4 Specs (all PowerBook G4 Tech Specs) | everymac

Take care & good luck!🌻🐝

I forget exactly where the serial number stickers were on these models. In addition to checking inside the battery bay, check beneath the keyboard and inside the memory compartment.