My L755 has always struggled with battery life. From new, it was only managing a little over one hour and it was no surprise when it booted up one day with an ugly red cross over the battery and a suggestion that I might like to consider replacing the battery.
I went to Amazon and bought a 'genuine brand new Toshiba battery'.
The battery arrived, it is the right part number, but I was immediately suspicious because the battery had stickers on it that did not seem correct and a manufacturing date in 2010.
The sticker that bothered me most stated that it might contain NiCad, NiMH or Li-Ion cells -
I am sure that Toshiba are more professional than to randomly build the packs.
Sure enough, when fitted to the laptop I get a flashing battery light and it shows no interest in booting up. Should I give it a few hours to charge and try again, or go straight to Trading Standards to try and get the cowboy supplier investigated?
Notebook should be able to boot up also if the battery is empty but connected to the AC adaptor.
If the battery is new, you should consider an longer charging. But as mentioned: even if its empty, the unit should power on and the battery should start to charge after the AC adaptor has been connected.
From my point of view and according to your message, it looks like the battery isn’t ok.
So would recommend to replace it.
By the way: I would recommend purchasing the battery from authorized Toshiba service partner in your country. In such case you can be 100% sure that such battery is an genuine product and compatible with your notebook. Many different internet reseller provide “low budget” and “low quality” batteries and sell such batteries as an “brand-name” product / article.