Due to high flexibility and ease of deployment, Unmanned Aerial Vehicle (UAV)-enabled mobile edge computing (MEC) has recently emerged to provide services for users to meet the demands of computing-intensive tasks at edge. However, the MEC-server mounted UAV is inappropriate for heavy-computation tasks owing to the limitation of energy supply and hardware cost, which may make for excessively high CPU temperature. To tackle this issue, this paper considers a UAV-and-basestation (BS) hybrid-assisted MEC network, where a hover-fly-hover mode is adopted to facilitate the provisioning of MEC services with the help of BS. Furthermore, a temperature control constraint is introduced to ensure the reliability of CPU at UAV. We aim to minimize the cruise duration of UAV with thermal-aware constraint by jointly optimizing UAV hovering trajectory, task scheduling strategy, and computation-and-communication resource allocation strategy. Although the formulated problem is non-convex, we decouple it into three subproblems and solve them in an iterative manner. Simulation results demonstrate that the proposed algorithm can not only satisfy the CPU temperature constraint but also help save the cruise duration.