I've recently had my Ideapad 730S start shutting down with some percentage of battery life remaining when on battery power. It's an immediate shut down with no warning. Conveniently, this seems to have started just beyond the warranty period. Based on visual battery percentage, I'd guess it's still showing about 20% or so, but can't confirm. System is up to date via Lenovo Service Bridge, Windows updated, etc. Any suggestions on what I can do or try?