I need a cheap, but also good laptop with the best possible price-performance ratio. He should not cost over 350 euro and go for occasional surfing and working with Word, Excel and PowerPoint.
Maybe a used Dell Lat. E6440?
Look here: https://www.notebooksbilliger.de/...440+633249
I have the devices from Dell actually only good experiences.
Since these are business devices you can z.b. Also even change the battery or the SSD.
https://geizhals.de/...at&hloc=de
https://www.notebooksbilliger.de/...g7+6hm83es
Better something like a Pentium or AMD A6 / 8 garbage laptop.
For the price I would buy a used laptop. I found an i5 Lenovo X230 with 8 GB RAM and 250 GB SSD, Win10 Professional for 200 euro. The is overhauled, the dealer still has a few in stock.