Java expert developer & tutor needed

(your todo please review and fix spelling + grammar)

I have to handle a client lead bot, which is collecting leads from internet and writes them into Excel.
Sadly the xls file is broken and it is not clear why it is broken.

It runs on java 8 (had to install from oracle)
It shows someting with spring boot on starting the application

Assuming an experienced java developer will have a quick win on this task.

Some technologies required:
- Java
- Excel Spreadsheets
- Spring-Boot
- especially high degree of expertise and experience
- a good way of explaining easily to me what needs to be done