What to do if your 18V RYOBI Mower won't turn on

First, check the battery is fully charged and installed.
Check that the red safety key is inserted & securely in position.
Fully extend the telescopic handles (if applicable) and ensure that a grass catcher or mulch-plug is securely installed too.
Next, press the middle start button, followed by squeezing either of the triggers.
Once the mower starts, keep holding the triggers, and release the start button.
To turn the mower off, let go of the triggers.

Applicable Models

R18LMWP4, R18XLMW24, RLM18X33S40, OLM1840BL, RLM1840BLX6