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Flashing custom firmware

(CORE One, MK4/S, MK3.9/S, MK3.5/S)

Relevant for

MK4
MK3.9
MK3.5
MK4S
MK3.9S
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The Prusa CORE One, and the Original Prusa MK4/S, MK3.9/S, and MK3.5/S are equipped with an xBuddy board

In their factory state, our printers only accept official firmware. To flash any unofficial firmware to the printer, it is necessary to break the appendix seal on the xBuddy board

Breaking the appendix seal won’t void your warranty, so you are free to flash custom firmware.
However, since there is no way for us to verify or test every single custom firmware on the internet, we disclaim liability for any kind of damage or harm a printer with a broken seal may cause (e.g. in case of a fire). 
So, please, don’t mindlessly flash suspicious files! 

Before attempting this procedure, carefully review the description and the photo below. 

To break the appendix, open the electronics box and locate a safety seal on the xBuddy board, with an exclamation mark on it. Then, take a small flathead screwdriver or very thin sharp pliers and break off the thin middle part of the seal

Once the appendix seal is broken, flashing firmware can be done following the procedure in the dedicated article on firmware updating

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1 comment

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Jürgen
"... we disclaim liability for any kind of damage or harm a printer with a broken seal may cause (e.g. in case of a fire)."

I don't think it is legally acceptable to tell a customer (who is a consumer): "We have provided this handy little seal for you. Feel free to break it, it won't even affect your warranty -- but the product may no longer be CE or UL compliant regarding fire safety." Which seems to be what this disclaimer says. You can't encourage a consumer to override a seal or fuse, and then disclaim product liability.

Prusa, could you please clarify the compliance and product liability implications?
Jan Kratochvíl
Hello. We do not encourage breaking this seal. The printer is designed to work with the seal intact. However, it is not fair to refuse your warranty for a faulty part every time we notice a broken seal, especially since the seal is meant for flashing the printer with custom firmware. In such cases, your warranty can be honored if we confirm that your issue was not caused by any modifications or installations you performed on the printer.