I just purchased a second hand LEGO Mindstorms Home EV3. The brick turns on, allows firmware update, etc. However, after about 2 minutes the unit makes a noise, LED's turn red, and 3 icons appear.

  1. Triangle with exclamation point
  2. Gage with arrow pointing to the right (I assume overheat?)
  3. Manual with exclamation point

Question: does anyone know what this error message indicates?

There appears to be some battery corrosion as if it was stored and the batteries leaked. Additionally Ports 1 and 2 indicate "Error" or "Unknown" and sometimes they think a Sound DB sensor is plugged in even though nothing is plugged in.

enter image description here

1 Answer 1


There is a full map of the EV3 user interface here.

Although the popup in the photo is in the diagram, it is not labeled. So we have to go digging around the EV3 source code to find out what it means. The icons can be found in this bitmap. The icons are mapped to names here. Using this information, we can deduce that from left to right, the icons are WARNSIGN, WARN_POWER and TO_MANUAL. Further search of the code reveals two conditions where all 3 of these icons appear together. WARNING_TEMP and WARNING_CURRENT.

So either the battery has high temperature or the brick is using too much current. Given the statements about the malfunctioning input ports and the battery leakage damage, I would suspect that the battery leakage has cause some sort of short circuit that is causing high current usage. You could try removing the cover and cleaning up the damage with isopropyl alcohol. Although to get to the back side of the circuit board, you have to desolder the battery terminals.

  • I would also contact the seller, and ask them if they knew the circuit board was damaged. Commented Jun 22, 2022 at 20:22
  • ok thanks for my answer
    – LKBricks
    Commented Jun 30, 2022 at 6:59

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