Diagnose a problem when you don't have access to a Blogger Account

Supposed a blog reader request help regarding a problem with their blog, but you do not have access to his or her account of what ever blogging platform he or she is using, what can you do.

Sometimes you can spot the problem by clicking VIEW > PAGE SOURCE (FireFox or just VIEW > SOURCE in Internet Explorer. A new window will open with the page source (source code) that is used to display your blog with a web browser.

I was asked about a problem a blogger had with replacing a graphic in her blog Header, so without access to her account, I had to view the page source of her blog. I found this in the page source:

#header-wrapper {
float: left;
width: 198px;
height: 148px;
background: url(https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi06LsA6fWprFKyNBhJFPyzOtL1VMPKvGRz59ZlXydCOwxrRxenvfzK67F396bP-qVJbu3UhKN95d8PdNx2oiX4r7ROX_6a2h-PVtDkhWUJ-LrTW9TAIqCv21LVozyowSqAPuODdPzQepk/s1600/img1.jpg);
border: 1px solid #939A3C;

The URL of the graphic for background of her blog Header seem to be the one highlighted in red in the scroll box above. So the only thing I can tell her is to replace that

graphic background of the graphic image URL with another image uploaded to the web, and this is what I am going to tell her.

The only problem is, when I opened a new tab in the same window in FireFox which has tabbed browsing, which is my favorite browser and which is a browser recommended by Google Blogger, pasted her image URL into the address bar, instead of taking me to the web page with only the image she used as background graphic for her blog Header, I was asked to download a file which is very surprising. If her graphic image is not on the web, but only hosted by a file host which host the graphic image file and only give your the URL to download the image file, I would expect no image would be displayed in her blog Header. But when I viewed her blog, there is an image in the blog Header.

This puzzled me and I do not know what is the situation. I can only explain to her, asked her what she did, and see if anything can be done. If there is any development, I will put an update here.