I discovered that somewhere inside the telephone lived an am

1.楼主理解没错,此句的确是（全部）倒装句型.
2.主句主语I,主句谓语discovered,that somewhere inside the telephone lived an amazing person是宾语从句.
3.宾语从句中,真正的主语是an amazing person,谓语是lived,地点状语是somewhere inside the telephone.
该从句的正常句序为：an amazing person lived somewhere inside the telephone.
4.此宾语从句是个典型的完全倒装句型,其结构为：(地点)状语 + 谓语 + 主语（主语要求为名词短语）.
此类倒装句型一般是把表地点/时间/方向/趋势等的状语(一般是介宾短语或副词)提前以示强调,再把主谓倒装即可.
再如：In the forest lived a tiger.
Away went the fox.
5.另：如果主语是代词时,则不能使用倒装句型.
如：Here he comes.
楼主可以对比一下：Here comes the bus.