I repeat, what is the infected file name (you have told us the trojan name already and isn’t that helpful), where was it found e.g. (C:\windows\system32\infected-file-name.xxx) ?

You aren’t accessing the chest, just instructing avast to send it to the chest. To do so you need to open the Simple User Interface, as you would do to run a scan, right click or select the menu and then click Virus Chest. You will see it comprises several sections, the one you are interested in is Infected Files. There is a System Files section that contains some back-up copies of important system files in case the original is infected, don’t worry about these.