This tool generates CPU loads.
This tool launches several Android Services that continue to calculate SHA1 value of 2MB buffer that is filled by random data. You can control how many Android Services are launched by pushing button. Basically I think that CPU load is highest when you launch number of services as same as the number of the CPU Core.

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It seems this tool is too hevy. According to user feedback several devices were broken. So please use this app carefully. But this tool are using just MessageDigest#update() and MessageDigest#digest().
https://developer.android.com/reference/java/security/MessageDigest#update(byte[])
https://developer.android.com/reference/java/security/MessageDigest#digest()
So if device is broken it is device's problem because device must ensure that all Android API work properly. And I think you can ask manufacture for repair.
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