External Lenovo connected to MacBook stuck in power saving mode

Hi, I have been using a Lenovo monitor connected to my MacBook via HDMI and haven't had any issues until a few days ago when I accidentally unplugged the power cord and eventually the battery of the MacBook drained to zero. After I replugged the power cord and the laptop recharged the monitor would come on when I pressed the power button but then would go into power saving mode. I have restarted the MacBook, unplugged the monitor and even updated the laptop and nothing is working. I would greatly appreciate any advice. Thank you!