Greetings @alexao.
Thanks for posting in our community.
Sorry to read that you are having multiple issues with your laptop and I will do my best to help you with those concerns. Battery life is an estimated maximum. Actual battery life may vary based on many factors, including screen brightness, active applications, features, power management settings, battery age and conditioning and other customer preferences.
For the steps on how to extend the battery life, we suggest for you to apply the steps provided in this link https://pcsupport.lenovo.com/es/en/solutions/ht069687-easy-ways-to-extend-your-battery-life-ideapadlenovothinkpad-laptops. Once done, observe your system afterwards.
As for the issue with the overheating when the charger is plugged in, please make sure that your system has the latest BIOS and driver updates using Lenovo Vantage app. Here's a link that contains a short clip on how to do it.
In addition, check if there are any pending Windows Updates (including optional updates) that needs to be installed. Go to Settings > Update & Security > Windows Update > click on Check for updates then restart your machine afterwards.
Update us how things go.
Rodney_Lenovo